System and method for measuring slope or tilt of a bone cut on the muscular-skeletal system

ABSTRACT

A system and method is disclosed herein for measuring bone slope or tilt of a prepared bone surface of the muscular-skeletal system. The system comprises a three-axis accelerometer for measuring position, rotation, and tilt. In one embodiment, the three-axis accelerometer can be housed in a prosthetic component that couples to a prepared bone surface. The system further includes a remote system for receiving, processing, and displaying quantitative measurements from one or more sensors. A bone is placed in extension. The three-axis accelerometer is referenced to a bone landmark of the bone when the bone is in extension. The three-axis accelerometer is then coupled to the prepared bone surface with the bone in extension. The slope or tilt of the bone surface is measured. In the example, the slope or tilt of the bone surface corresponds to at least one surface of the prosthetic component attached thereto.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. provisional patentapplication No. 61/803,078 filed 18 Mar. 2013. The disclosure of whichis incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The invention relates in general to medical and surgical procedures andmore particularly to aligning medical devices to precise locations on orwithin a patient's body.

BACKGROUND OF THE INVENTION

Orthopedic alignment currently involves cycles of trial and error. Forexample, leg alignment requires a technique that approximates alignmentin which the surgeon makes one of the distal femoral cut and theproximal tibial cut based on experience, mechanical jigs, and visualalignment. Typically, the proximal tibial cut is made so as to removethe least amount of the proximal tibia, while ensuring sufficientremoval of diseased or otherwise undesirable bone. The remaining femoralcuts are made to complete shaping of the femur to receive a femoralprosthesis. After the femoral and tibial cuts are complete, the femoralprosthesis and the tibial prosthesis, or trial versions thereof, aretemporarily implanted and the surgeon reviews leg alignment. Typically,no adjustments are made if the leg is within a few degrees varus orvalgus of the mechanical axis. An insert has a bearing surface thatallows articulation of the leg. A set of shims can be coupled to theinsert. The shims are used to change the thickness of the insert. A shimand insert combination is chosen that produces the best subjectivemovement characteristics of the joint through a full the range ofmotion. The surgeon may modify the bone or perform soft tissuetensioning to affect load, rotation or alignment characteristics. Ingeneral, the implant procedure is performed using the subjective skillsof the surgeon to achieve appropriate leg alignment, rotation, balance,and soft tissue tension—loading.

Even with mechanical jigs, trialing, and advanced prosthetic components,outcomes including functional efficacy, patient comfort, and longevityof the prosthesis may not always be highly predictable, especially ifprocedures are performed by physicians and surgeons with differentlevels of skill, experience, and frequency of repeating an individualprocedure. This may be confirmed by various reports in the literaturethat suggest a positive relationship between outcomes and the numbers ofprocedures performed annually by individual surgeons.

Accurately determining and aligning an implant orientation is adifficult process requiring expensive equipment. A simple, efficientmethod is needed to reduce medical costs and time of the surgicalprocedure, while maintaining accuracy.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of present invention will become more fully understood fromthe detailed description and the accompanying drawings, wherein:

FIG. 1A illustrates a simplified view of directions of motion referredto herein;

FIG. 1B illustrates the comparison between vargus and valgus;

FIG. 1C illustrates a simplified view of a physician using at least oneembodiment of a motion and orientation sensing device (e.g., a surgicaltracking system) with a computer display (e.g., a surgical trackingdisplay system);

FIG. 2 illustrates a top view of a tibia and associated reference axis;

FIG. 3 illustrates a side view of a tibia and associated reference axis;

FIG. 4 illustrates a user obtaining a reference axis by moving a sensor;

FIG. 5 illustrates a user obtaining an alignment by moving an orthopedicsystem;

FIG. 6 illustrates a user obtaining alignment data using a sensor;

FIGS. 7 and 8 illustrates a user moving an orthopedic system inextension to obtain alignment data;

FIGS. 9 and 10 illustrates a user moving an orthopedic system in flexionto obtain alignment data;

FIGS. 11 and 12 illustrates a user moving an orthopedic system inflexion to obtain alignment data

FIGS. 13 and 14 illustrates a user moving an orthopedic system inelevated extension to obtain alignment data;

FIG. 15 illustrates a user moving an orthopedic system in elevatedextension to obtain alignment data;

FIG. 16 illustrates an electronic display showing a schematic of asensor, with orthopedic parametric values and a display of theorthopedic system;

FIGS. 17-36 illustrates portions of a software display of a user assistcomputer program;

FIGS. 37-38 illustrates various device zeroing configurations;

FIG. 39 illustrates a device orientation to obtain reference axis data;

FIG. 40 illustrates an adapter and device that can be coupled to acutting jig;

FIG. 41 illustrates the adapter and device coupled together;

FIG. 42 illustrates a cutting jig and the associated adapter and sensordevice;

FIG. 43 illustrates an incorporated cutting jig system including theadapter and sensor device;

FIG. 44 illustrates the incorporated cutting jig system in a cuttingposition in an extended orthopedic system;

FIG. 45 illustrates the incorporated cutting jig system in a cuttingposition in a flexion orientation, changing vargus and valgus of thecutting jig;

FIG. 46 illustrates the incorporated cutting jig system in a cuttingposition in an extension system, changing the A-P angle of the cuttingjig;

FIG. 47 illustrates two cutting jig systems being aligned;

FIG. 48 illustrates a femur rotation guide;

FIG. 49 illustrates using the femur rotation guide to adjust condialorientation;

FIG. 50 illustrates a tibia reference tool used for alignment;

FIG. 51 illustrates another view of the tibia reference tool used foralignment;

FIG. 52 illustrates a method of measuring joint alignment between firstand second bones;

FIG. 53 illustrates another method of measuring joint alignment betweenfirst and second bones;

FIG. 54 illustrates another method of measuring joint alignment betweenfirst and second bones;

FIG. 55 illustrates a method of measuring alignment of a tibia to amechanical axis of a leg;

FIG. 56 illustrates another method of measuring alignment of a tibia toa mechanical axis of a leg;

FIG. 57 illustrates another method of measuring alignment of a tibia toa mechanical axis of a leg;

FIG. 58 illustrates method of measuring alignment of a femur;

FIG. 59 illustrates another method of measuring alignment of a femur;

FIG. 60 illustrates another method of measuring alignment of a femur;

FIG. 61 illustrates a method of measuring slope or tilt of a preparedbone surface of a bone;

FIG. 62 illustrates another method of measuring slope or tilt of aprepared bone surface of a bone;

FIG. 63 illustrates a method of measuring slope or tilt of a tibialprosthetic component coupled to a tibia;

FIG. 64 illustrates another method of measuring slope or tilt of atibial prosthetic component coupled to a tibia;

FIG. 65 illustrates another method of measuring slope or tilt of atibial prosthetic component coupled to a tibia;

FIG. 66 illustrates a method of referencing a three-axis accelerometerto measure location, tilt, and rotation of the muscular-skeletal system;

FIG. 67 illustrates another method of referencing a three-axisaccelerometer to measure location, tilt, and rotation of themuscular-skeletal system;

FIG. 68 illustrates a method of kinetic assessment, joint modification,and installation of a final prosthetic joint;

FIG. 69 illustrates a method of kinetic assessment, joint modification,and installation of a final prosthetic joint;

FIG. 70 illustrates another method of kinetic assessment, jointmodification, and installation of a final prosthetic joint;

FIG. 71 illustrates another method of kinetic assessment, jointmodification, and installation of a final prosthetic joint;

FIG. 72 illustrates another method of kinetic assessment, jointmodification, and installation of a final prosthetic joint;

FIG. 73 illustrates a method of kinetic knee assessment for installing aprosthetic knee joint;

FIG. 74 illustrates a method of adjusting a contact point of a jointsystem where a prosthetic component is coupled to a bone;

FIG. 75 illustrates another method of adjusting a contact point of ajoint system where a prosthetic component is coupled to a bone;

FIG. 76 illustrates another method of adjusting a contact point of ajoint system where a prosthetic component is coupled to a bone;

FIG. 77 illustrates a method of adjusting a tibial prosthetic componentin a knee joint;

FIG. 78 illustrates another method of adjusting a tibial prostheticcomponent in a knee joint;

FIG. 79 illustrates another method of adjusting a tibial prostheticcomponent in a knee joint;

FIG. 80 illustrates another method of adjusting a tibial prostheticcomponent in a knee joint;

FIG. 81 illustrates method of measuring tilt of a prepared bone surfaceof a muscular-skeletal joint;

FIG. 82 illustrates another method of measuring tilt of a prepared bonesurface of a muscular-skeletal joint;

FIG. 83 illustrates another method of measuring tilt of a prepared bonesurface of a muscular-skeletal joint;

FIG. 84 illustrates a method of measuring medial-lateral tilt of aprepared bone surface of a knee joint;

FIG. 85 illustrates another method of measuring medial-lateral tilt of aprepared bone surface of a knee joint;

FIG. 86 illustrates another method of measuring tilt of a prepared bonesurface of a muscular-skeletal joint;

FIG. 87 illustrates another method of measuring tilt of a prepared bonesurface of a muscular-skeletal joint;

FIG. 88 illustrates another method of measuring tilt of a prepared bonesurface of a muscular-skeletal joint;

FIG. 89 illustrates a method of measuring medial-lateral tilt of adistal end of a femur of a knee joint;

FIG. 90 illustrates a method of generating a reference position;

FIG. 91 illustrates axes associated with a sensor and rotations;

FIG. 92 illustrates a plot of the acceleration in the x direction versusangle of inclination of a sensor;

FIG. 93 illustrates a descriptive figure of a method in accordance withan embodiment;

FIGS. 94A and 94B illustrate horizontal orientations used in calibrationin accordance with an embodiment; and

FIG. 95 illustrates a vertical orientation used in calibration inaccordance with an embodiment.

DETAILED DESCRIPTION OF EMBODIMENTS

The following description of embodiment(s) is merely illustrative innature and is in no way intended to limit the invention, itsapplication, or uses.

For simplicity and clarity of the illustration(s), elements in thefigures are not necessarily to scale, are only schematic and arenon-limiting, and the same reference numbers in different figures denotethe same elements, unless stated otherwise. Additionally, descriptionsand details of well-known steps and elements are omitted for simplicityof the description. Notice that once an item is defined in one figure,it may not be discussed or further defined in the following figures.

It will be appreciated by those skilled in the art that the words“during”, “while”, and “when” as used herein relating to circuitoperation are not exact terms that mean an action takes place instantlyupon an initiating action but that there may be some small butreasonable delay, such as a propagation delay, between the reaction thatis initiated by the initial action. Additionally, the term “while” meansthat a certain action occurs at least within some portion of duration ofthe initiating action. The use of the word “approximately” or“substantially” means that a value of an element has a parameter that isexpected to be close to a stated value or position. However, as is wellknown in the art there are always minor variances that prevent thevalues or positions from being exactly as stated.

The terms “first”, “second”, “third” and the like in the Claims or/andin the Detailed Description are used for distinguishing between similarelements and not necessarily for describing a sequence, eithertemporally, spatially, in ranking or in any other manner. It is to beunderstood that the terms so used are interchangeable under appropriatecircumstances and that the embodiments described herein are capable ofoperation in other sequences than described or illustrated herein.

Processes, techniques, apparatus, and materials as known by one ofordinary skill in the art may not be discussed in detail but areintended to be part of the enabling description where appropriate. Forexample specific methods of attaching a surgical device onto thesurgical device holder, however one of ordinary skill would be able,without undo experimentation, to establish the steps using the enablingdisclosure herein.

The terms precision and resolution can be used herein to specificallyhave the standard definitions. Precision will connate the variation fromexactness. Resolution will have the customary definition of the smallestmeasurable interval. The orientation of the x, y, and z-axes ofrectangular Cartesian coordinates is assumed to be such that the x and yaxes define a plane at a given location, and the z-axis is normal to thex-y plane. The axes of rotations about the Cartesian axes of the deviceare defined as yaw, pitch and roll. With the orientation of theCartesian coordinates defined in this paragraph, the yaw axis ofrotation is the z-axis through body of the device. Pitch changes theorientation of a longitudinal axis of the device. Roll is rotation aboutthe longitudinal axis of the device.

The orientation of the x, y, z axes of rectangular Cartesian coordinatesis selected to facilitate graphical display on computer screens havingthe orientation that the user will be able to relate to most easily.Therefore the image of the device moves upward on the computer displaywhenever the device itself moves upward for example away from thesurface of the earth. The same applies to movements to the left orright.

The terms ‘motion sensing’ and ‘tilt sensing’ and ‘orientation’ is alsointended to have specific meaning. ‘Motion sensing’ indicates thedetection of movement of a body that exceeds a specified threshold inone or more coordinate axes, for example the specific threshold in oneor more Cartesian axes in terms of both static and dynamic acceleration.‘Heading’ is defined as the orientation of longitudinal axis of themotion of the motion and orientation sensing module or device andmovement in a direction. ‘Tilt’ is defined as the orientation of a bodywith respect to a zenith. The term slope is used interchangeable withthe term “tilt.” Tilt sensing′ indicates the measurement of accelerationattributable to gravity in one or more axes. ‘Orientation’ includes yawas well as ‘tilt.’ Note that although accelerometers are provided asenabling examples n the description of embodiments, any tracking device(e.g., a GPS chip, acoustical ranging, magnetometer, gyroscope,inclinometers, MEMs) can be used within the scope of the embodimentsdescribed.

Note that the term flexion value is used herein. For purposes of thisdisclosure a flexion value of approximately 180 degrees is fullextension, and any value other than 180 degrees is a joint in flexionwhere the bones on either side of the joint intersect form an angle.Note also tolerance values are those known by one of ordinary skill inthe arts, for example subjective tolerance on angle measurements can be1 to 3 degrees.

At least one embodiment is directed to a kinetic orthopedic (e.g., knee)balancer system to aid a surgeon in determining real time alignment andloading of orthopedic implants. Although the system is generic to anyorthopedic surgery (e.g., spinal, shoulder, knee, hip) the followingexamples deal with knee surgery as a non-limiting example of anembodiment of the invention.

The non-limiting embodiment described herein is related to quantitativemeasurement based orthopedic surgery and referred to herein as thekinetic system. The kinetic system includes a sensor system thatprovides quantitative data and feedback that is displayed visuallyand/or audibly and/or haptically to a surgeon. The kinetic systemprovides the surgeon real time dynamic data regarding loads in eachcompartment of the knee, tibio-femoral implant contact and congruencythrough a full range of motion, and information regarding angular bonycuts and leg alignment.

In general, kinetics is the study of the effect of forces upon themotion of a body or system of bodies. Disclosed herein is a system forkinetic assessment of the muscular-skeletal system. The kinetic systemcan be for the installation of prosthetic components or for monitoringand assessment of permanently installed components to themuscular-skeletal system. For example, installation of a prostheticcomponent can require one or more bone surface to be prepared to receivea device or component. The bone surfaces are cut to place the prostheticcomponent in a relational position to a mechanical axis of a joint. Thekinetic system is designed to take quantitative measurements of at leastthe load, position of load, and alignment with the forces being appliedto the joint similar to that of a final joint installation. The sensoredmeasurement components are designed to allow ligaments, tissue, and boneto be in place while the quantitative measurement data is taken. This issignificant because the bone cuts take into account the kinetic forceswhere a kinematic assessment and subsequent bone cuts could besubstantial changed from an alignment, load, and position of load oncethe joint is reassembled.

Measurements data supplement the subjective feedback of the surgeon toensure optimal installation. The quantitative measurements can also beused to determine adjustments to bone, prosthetic components, or tissueprior to final installation or to fine tune the installation. Permanentsensors in the final prosthetic components can provide periodic datarelated to the status of the implant in use. Data collectedintra-operatively and long term can be used to determine parameterranges for surgical installation and to improve future prostheticcomponents. The physical parameter or parameters of interest caninclude, but are not limited to, measurement of load, force, pressure,position, displacement, density, viscosity, pH, spurious accelerations,and localized temperature. Often, several measured parameters ordifferent measurements are used to make a quantitative assessment.Parameters can be evaluated relative to orientation, alignment,direction, displacement, or position as well as movement, rotation, oracceleration along an axis or combination of axes by wireless sensingmodules or devices positioned on or within a body, instrument,appliance, vehicle, equipment, or other physical system.

FIG. 1A illustrates the basic directions and motions discussed hereinwith reference to a surgeon/user 180 and a patient 111. For example, thevertical axis 100A is perpendicular to the table 117 upon which thepatient 111 lies. The vertical axis 100A points to the anteriordirection. The axis 100B is parallel but opposite to the vertical axis100A and points to the posterior direction. In the patient configurationshown corresponding to the left leg of patient 111 the axis 101 pointsto the lateral side of the knee while the axis 102 points to the medialside of the left knee. Thus, if a device is situated at the verticalaxis 100A in the left knee and pivoted about the 103 and 104 axis in the101 axis direction the device is being rotated in the lateral direction.Conversely, if the device is pivoted about the 103 and 104 axis in the102 axis direction the device is being rotated in the medial direction.The knee joint move through an arc corresponding to axis 101A and axis102A when rotated laterally and medially. In a first example of a pivotpoint the heel of the foot can be placed at a fixed position on theoperating table along axis 104 to 103. The knee joint pivots off of heelof the leg but can be rotated along the axis 101A and the axis 102A. Ina second example of a pivot point, the heel is lifted off of theoperating table and the leg is pivoted off of the hip joint. The pivotpoint is the femoral head of the femur. Typically, the hip joint is at afixed position on the operating table. The knee joint pivots off of thefemoral head of the femur but can be rotated along the axis 101A and theaxis 102A. The angle of the device in the knee joint can be changed bymoving the pivot point of the heel in the direction 104 or the direction103. For example, moving the heel in direction of the axis 104 will movethe joint towards the posterior position 100B that correspondinglychanges the angle of flexion.

FIG. 1B illustrates a muscular skeletal system showing a medial lateralline 191A. The mechanical axis of a non-deformed leg is illustrated bythe vertical dashed line 191B as illustrated in view 191. View 193illustrates a leg having a varus deformity. A varus angle 193Aillustrates a varus offset with respect to the mechanical axis of anon-deformed leg. View 195 illustrates a valgus deformity. A valgusangle 195A illustrates a valgus offset with respect to the mechanicalaxis of a non-deformed leg.

FIG. 1C illustrates a kinetic system that includes data displayed in aGUI 100 that can provide feedback to a surgeon 180 before/during/ andafter surgery on a patient 190. The GUI 100 is displayed on a screen105, which can be interacted with verbally (e.g., via microphone), orhaptically via a hand held control 130, and/or a mouse 110, and/or akeyboard 120. The GUI 100 can provide quantitative measurement data fromsensors (e.g., placed in implants, sensor on probes or surgicalinstruments). A computer, processor, digital signal process coupled toscreen 105 can run software programs that use the quantitativemeasurements from the sensors to visualize the on-going procedure,review measurement data, positions of the muscular-skeletal system,support modifications, and generate workflows based on the quantitativemeasurement data to support an optimal fit of the prosthetic components.Some non-limiting examples of information include: device type 140,device ID 142, company 144, CP rotation 146, Tibial rotation 148, HKA(Hip Knee Angle) 150, Tibia angle 152, A-P angle 154, flexion 156,implant 157 (e.g., tibial insert), localized load indicators 158, medialand lateral load scales 159 with ranges 160, joint orientation display162, a signal indicator button 163, a zeroing initiation button 164, atrack button 165, a clear button 171, an align button 166, a powerindicator 169, a power on button 170, and several other buttons that canbe used for other features 167 and 168.

Initial setup for a knee replacement surgery can involve evaluating apatient's x-rays of the knee joint. FIG. 2 illustrates an AP(anterior-posterior) view of the tibia/knee region. From the view inFIG. 2 the surgeon can define the varus/valgus plane (e.g. plane definedby plane intersecting line 200 and 210) and the depth of proposed bonecuts.

In addition to AP views the surgeon uses lateral views to determineposterior slope or determine cut angles. FIG. 3 illustrates a lateralview of the tibia knee area. As mentioned the lateral view allows thesurgeon to determine the anterior-posterior slope or how much of anangle to cut from anterior to posterior of the proximal tibia trying torecreate the patients natural slope. A bone jig can be attached to theproximal end of the tibia to prepare a proximal end of the tibia 220 forreceiving a prosthetic component. The bone jig can be adjusted toprovide a medial-lateral bone slope and an anterior-posterior boneslope. As disclosed herein below, quantitative measurements are used todetermine kinetic bone cuts under forces that are similar to what thefinal installed components will see. The kinetic system will providemeasurements of the misalignment of the tibia to the mechanical axis ofthe leg that will be compensated for in the bone jig adjustment for themedial-lateral portion of the tibial bone cut. Similarly, the kineticsystem will measure the misalignment of a femur to the mechanical axisof the leg, which can also be compensated for by one or more bone cuts.

In the non-limiting embodiment discussed herein we can usemedial-lateral views to determine an AP (anterior-posterior) slope. Forexample, two lines (330 and 340) intersecting the proximal tibial line300, will be defined below, but for now make angles 310 and 320respectively with the proximal tibial line 300, where the difference inthe angles (i.e., 320-310) can used in a tibial bone cut calculation.The first line, 330 bisects the tibial canal from the ankle to theinsertion of the ACL (e.g., on the anterior ⅓ of the tibial plateau) tothe native slope of the tibial plateau. The second line 340 runsparallel to the tibial crest 345 that intersects the tibial plateaunative line as well. In the example embodiment, the anterior-posteriorslope of the bone cutting jig is adjusted by quantitative measurementunder forces similar to that of the final prosthetic componentinstallation as will be disclosed herein below. The amount ofanterior-posterior slope cut into tibia 220 is often dictated by theknee joint and the knee joint components being used. For example, if theposterior cruciate ligament is removed an insert with a post is oftenused to provide support to the joint. An anterior-posterior slope is cutinto tibia 220 to support range of motion of the joint in flexion inconjunction with the post.

The measurement device or sensored device comprises at least a pressuresensor system to measure load magnitude and position of load magnitude.The measurement device further includes at least one three-axisaccelerometer. In one embodiment, the three-axis accelerometer isreferenced to gravity to measure position, rotation, and tilt or slope.The sensing system can be integrated into a prosthetic component. In theexample, the sensored device is an intra-operative trial insert. Thetrial insert includes at least one articular surface that supportsmovement of the joint. As shown, herein the insert has two aritcularsurfaces. The trial insert is substantially similar in size to a finalinsert. The trial insert allows all the ligaments, tendons, tissue, andbone structures that apply forces to the joint to be in place during thekinetic assessment to provide quantitative data on load, position ofload, and alignment. The trial insert can be wired or wireless fortransmitting data to a remote system. The remote system can include adisplay, software, and a microprocessor, microcontroller, or digitalsignal process. The remote system is typically outside the surgicalfield but can be viewed by the surgical team. The sensing system canalso be in a trial tibial prosthetic component or a femoral prostheticcomponent. Similarly, the measurement device can be integrated into apermanent prosthetic component. An example for a knee applicationintegrating the measurement device into a tibial prosthetic component.Alternatively it could be integrated into the permanent femoralprosthetic component or insert.

In FIG. 4 a trial insert or sensored insert 425 is referenced toestablish reference planes for position, rotation, and tilt or slope.The insert 425 is referenced to a first plane. In the example, insert425 is referenced to the operating table. The insert 425 is thenreferenced to a second plane. The second plane is perpendicular to thefirst plane. The accelerometer in the sensored insert 425 measures theplane of the operating table in a first direction and then the sensoredinsert is rotated 180 degrees and a second measurement is taken. The twoaccelerometer measurements are averaged to remove any slope theoperating table may have. The accelerometer is zeroed to the plane ofthe operating table. The accelerometer is then zeroed to the plane thatis perpendicular to the table. A block can be held at a 90 degree angleto the plane of the table and insert 425 held against the block andzeroed to the plane. Alternatively, a structure can be attached orcoupled to the table that has a reference plane that is perpendicular tothe surface of the table. Insert 425 can be held to the structure andzeroed to plane perpendicular to the operating table surface. A moredetailed explanation of the referencing process is disclosed in FIGS. 37and 38.

A reference position of the joint is established to support furthermeasurement and positioning of the joint. In the example, the leg isplaced in a position of approximately extension. The position does nothave to be in extension in the strictest definition of the term but aposition that the surgeon can repeatably place the leg in. In oneembodiment, a tibia reference is captured. The tibia referencerepresents the position of the tibia when the leg is in full extension.For example, the leg can be placed with the heel touching the operatingtable at a fixed location. Alternatively, the distal portion of the legcan be placed in a leg holder for repeatable placement and positioning.Upon placing the leg in approximately extension insert 425 will bereferenced to a bone landmark or other repeatable reference related tothe leg in extension. In the example, the position or angle of a tibialcrest 427 is measured by the surgeon 400 when the leg is in extension.Posterior edges of insert 425 are held against a tibial crest 427. Thetibial crest is below the tibial tubercle and provides a large surfacearea to contact. Insert 425 is held approximately perpendicular to theplane of the surface of the operating table on the tibial ridge. Thesurgeon will move 420 the posterior of insert 425 against the tibialcrest until it is stabilized against the rcrest. A three axisaccelerometer 410 in insert 425 measures the an angle of tibial crest427 in extension. The measurement data is transmitted to a remote systemhaving a GUI. The GUI displays the angle of insert 425 relative tovertical and the angle of tibial crest 427. With the leg in extensionthe angle of insert 425 is held within −2 and 2 degrees of vertical toensure an accurate measurement. In one embodiment the system capturesthe angle of the tibial crest when the angle of insert 425 is within −2degrees and +2 degrees. Typically, the angle of the tibial crest isapproximately 3 degrees for a large portion of the population. The GUIwill show the angle of the tibial crest on an indicator from themeasurement data transmitted from accelerometer 410 to the remotesystem. Insert 425 is then referenced to this angle whereby the GUIindicates that the leg is in extension when the tibia is placed in thesame position. In one embodiment, a flexion indicator of the GUI is usedto display the angle of insert 425 measured to vertical. A tray rotationindicator of the GUI is used to display the angle of tibial crest 427.Thus, a bone landmark has been referenced by the system. A position ofextension is indicated on the GUI when the bone landmark is placed inthe reference position. In the example, GUI indicators are used morethan once to indicate certain steps of a procedure to reduce the numberof indicators and reduce clutter on the display. The user of the systemcan then rapidly synthesize the information being displayed to reducesurgical time. In one embodiment, the AP (anterior-posterior) slope ortilt indicator will be displayed on the display of the remote systemafter reference the tibia for a position of extension.

In FIG. 5 a surgeon 500 can place a sensored insert 510 on a proximalportion 520 of tibial bone cutting jig 530. In one embodiment, a shimhaving a tab is coupled to insert 510. The tab of the shim is coupled tobone cutting jig 530. In the example, the tab is inserted into a cuttingslot of bone cutting jig 530. Sensored insert 510 can be used to definethrough quantitative measurements the medial-lateral (ML) andanterior-posterior (AP) bone cuts of tibial bone cutting jig 530. Forexample, the accelerometer in sensored insert 510 can be used to measuretilt or slope to obtain a measurement of the jig angle in the AP planeprior to the cut. Furthermore, sensored insert 510 can be similarlyplaced on a distal femoral jig to define if the sagittal plane isparallel to the tibial cut or to produce a cut offset to the tibial cut.The GUI 100 flexion angle 156 will depict the angle of the proposedtibial cut in the AP plane. The process of using sensored insert withbone cutting jigs will be disclosed in more detail hereinbelow.

In FIG. 6 the surgeon 400 takes a sensored insert 425 and places it intoa knee tibial prosthetic component 600. Tibial prosthetic component 600can be a trial or permanent component. Tibial prosthetic component 600can be fixed to the tibia that supports movement. For example, tibialprosthetic component 600 can be held to the tibia via a single pin thatallows rotation. Typically, how tibial prosthetic component 600 isaligned to the tibia is a choice of the surgeon. In one embodiment,tibial prosthetic component 600 is positioned or aligned to a bonereference whereby tibial prosthetic component 600 can be placedconsistently from patient to patient. The initial placement or alignmentof tibial prosthetic component 600 is a reference position. In general,leg 610 is in flexion when inserting sensored insert 425 into the kneejoint. In one embodiment, insert 425 is inserted into a tibial tray oftibial prosthetic component 600. Insert 425 can include a shim toincrease or decrease insert height or thickness. A change in insert 425thickness is required if the joint is too loose or too tight when movingthrough the range of motion. The tibial tray retains insert 425 in afixed position relative to tibial prosthetic component 600. Insert 425couples to a femoral prosthetic component and tibial prostheticcomponent 600. Insert 425 has at least one articular surface. In theexample, has two articular surfaces that allow the leg to move through arange of motion. The leg can then be placed in extension 620 as measuredby the accelerometer and indicated on GUI 100. The AP box 154A on theGUI is clicked to measure the AP slope or tilt of the proximal tibialcut as referenced to the tibial crest or any chosen referenced plane(e.g., cutting rod etc. . . . ). In general, the accelerometer in insert425 is coupled to the tibia and measures the anterior-posterior slope ofthe bone cut on the proximal end of the tibia relative to the referencedtibial crest. Thus, the A-P slope measurement can be made independent ofthe leg position.

FIGS. 7 and 8 illustrate the surgeon 400 or surgical team interfacingwith the GUI to set A-P slope. In particular, box 154A and box 156A ofthe GUI are shown. Box 154A and Box 156A respectfully correspond to A-P(anterior-posterior) slope and flexion position of the leg. In FIG. 7the leg is moved into a position 701 of extension. As shown, themeasurement can indicate that the leg is hyper-extended with a negativereading (e.g. −3.5 degrees) relative to the floor. In the example, theproximal end of the tibia has been cut with an anterior-posterior slopeor tilt. The tibial tray of the tibial prosthetic component takes onthis slope when mounted to the tibia. Thus, the insert in a knee 610couples to the tibial tray of the tibial prosthetic component andmeasures the anterior-posterior slope thereof, which appears to show ahyper-extended knee. Note that in at least one embodiment the AP boxshows the slope, and the flexion angle is relative to the floor orgravity.

FIG. 8 illustrates measuring and setting the A-P slope on the GUI. Theleg remains in extension or the same position when the Tibial referencewas taken, until Box 154A is selected or clicked on. The measurement ofthe A-P slope is then taken. The flexion measurement of Box 156A istransferred to Box 154A. In the example, a positive slope for A-Pcorresponds to the anterior side proximal end of the tibia being higherthan the posterior side. Thus, the A-P slope as shown is measured at 3.5degrees in the example. The A-P slope measurement can be used to verifythat the cut was correct. If the A-P slope is incorrect as shown by Box154A correction or modification can be undertaken to change the slope.The A-P slope is stored in memory and can be used in furthercomputations and measurements. Changes to the slope can be re-referencedafter adjustments are made. The resultant position is the optimizedposition of the accelerometer in the sensored insert to define theproximal tibial A-P angles that were cut. As will be disclosed hereinbelow the sensored insert can be coupled to a tibial bone cutting jigpre-cut to define a tibial cut of 3.5 degrees A-P slope. In general, anA-P slope is useful to define flexion gap balance and equalize loadingwhen the leg is moved from extension into flexion.

FIGS. 9 and 10 illustrate the surgeon measuring the offset of the tibiato the mechanical axis of the leg. Prior to measuring the offset the CP(contact point) rotation is set. The CP rotation corresponds to areference position of the tibial femoral prothetic component to theprosthetic component. The Tibial Try Rotation box corresponds to areference position of thetbial tray. For example, many surgeons alignthe center of the tibal tray of the tibial prosthetic component to themedial third of the tibial tubercle or other landmark. As mentionedpreviously, the tibial tray can be pinned to the tibia in a manner thatallows rotation of the tibial prosthetic component from the referenceposition. A Tibial Rotation box on the GUI is selected or clicked oncethe reference position of the tibial tray is established. Any change inthe position of the tibial tray is indicated in the Tibial Rotation boxof the GUI. In one embodiment, the reference position is listed as zerodegrees in the Tibial Tray Rotation box. Alternatively, CP Rotation canindicate an amount of tray or insert rotation relative to the femoralcondylar contact on the tibial tray. Rotating the tibial prostheticcomponent will yield a positive or negative number in the Tibial trayRotation box depending on the direction of rotation. In one example,rotating the tibial prosthetic component can be used to affect theposition of load and the load magnitude over the range of motion. In oneembodiment, the GUI can indicate if the load magnitude is within apredetermined load range. Similarly, the GUI can indicate if theposition of load is within a predetermined position range. The value ofCP Rotation can be used in measurement and calculations of otherparameters such as the congruency of the tibial and femoral implantsthrough a full range of motion.

In FIG. 9, the knee joint is placed in flexion. In the example, thesensored insert is positioned to be at approximately a 45 degree angleto the plane of the surface of the operating table. The heel ispositioned in a fixed position to achieve the sensored insert angleoptimized position for reading outputs. The GUI directs the surgeon tothis flexion angle. In one embodiment, the heel is placed on the surfaceof the operating table. The position of the heel on the operating tableshould fixed in place as it will be a first pivot point for moving theknee joint. Surgeon 400 can hold and stabilize the ankle and heel tominimize movement during the measurement. In one embodiment an alignbutton on the GUI is pressed to initiate alignment measurements. Surgeon400 now follows a needle point graphic or tracking grid 930 on the GUIto begin rocking the knee back and forth with the heel 910 placed firmlyon the operating table in a stable position, to allow pivoting 920 onthe heel to define a plane to reference to. As shown, the knee joint ispivoted in the lateral direction and tracking grid 930 tracks themovement. In FIG. 10, the knee joint is pivoted in the medial directionand tracking grid 930 tracks the movement. The surgeon limits themovement within the range of tracking grid 930. In general, a maximum ofthe arc made by the knee joint is being identified by the system. Therange of the arc is less or equal to plus or minus 45 degrees fromvertical. In one embodiment, the arc is less than or equal to plus orminus 10 degrees from vertical. The maximum has to be within the rangeof tracking grid 930. Reducing the range of the arc improves measurementaccuracy since the same amount of measurements are taken for any givenrange. The knee joint is rocked to the medial side and the lateral sidemore than one time. In one embodiment, the knee joint can be rocked backand forth ten times or less to identify arc maximum. Increasing theanalog to digital converter accuracy can be used to reduce the number ofrocking motions. In one embodiment, the analog to digital converteraccuracy used in the measure of the arc maximum utilizes DAC's (digitalto analog converters) having 15-bit or greater accuracy. The number ofrocking motions can be reduced to four or less rocking motions using aDAC's of 15-bit or greater accuracy which reduces the time and effortrequired by surgeon to measure points in the arc. In general, theaccelerometer is referenced to three axis. A first axis corresponds tothe A-P (anterior-posterior) line of the knee joint. A second axiscorrespond to the M-L (medial-lateral) line of the knee joint. The thirdaxis is perpendicular to the plane of the first and second axis. In oneembodiment, the sensored insert is measuring and finding the maximumgravity in the X-direction or along the A-P line. At maximum gravity inthe X-direction raw tibial tray rotation of the tibial prostheticcomponent should be zero in the Y-direction or along the M-L line. Inthe system, Y-direction/X-direction is rotation and tilt isY-direction/Z-direction. If the measurement is not zero then the tibiahas tilt which is measured. The amount of tilt can be related to a varusor valgus angle relative to the mechanical axis. Thus, as the surgeon400 is pivoting 920 on the heel, the system searches for the Max G forthe sensored insert. The location of the maximum is used to determine anoffset from the mechanical axis of the leg. The offset corresponds to avarus-valgus angle for the tibia.

As mentioned previously, the knee joint can be positioned where thesensored insert is at a 45 degree angle relative to the surface of theoperating table to improve measurement accuracy. The aforementionedposition of the insert is a point where the axis of the A-P line and theaxis normal to the plane are approximately equal in terms of the effectof gravity. In one embodiment, the flexion box in the GUI can indicatewhen the sensored insert is in an optimal position prior to measuringthe leg alignment. For example, the number in the flexion box can changecolor to indicate that the leg is positioned for measurement.

FIG. 11 illustrates a measurement of a tibia angle relative to themechanical axis appearing on the GUI. In the example, the knee joint ispivoting 920 off of the heel of leg 610. The heel and ankle are heldtogether to prevent movement of the ankle. The knee joint is moved backand forth in a medial direction and a lateral direction a predetermineddistance as indicated in tracking grid 930 (e.g. needle point graphic onthe GUI). The back and forth movement of the joint is performed apredetermined number of times. A calculation of the varus-valgus angleappears on the display and is listed under tracking grid 930 as “Tibia”in the GUI. The varus-valgus angle corresponds to the medial-lateraltilt of the proximal end of the tibia. For example, the tibia is inalignment to the mechanical axis if the max G position corresponds tothe A-P line. If the max G position is offset from the A-P line then anoffset exists relative to the M-L line that can be converted to avarus-valgus angle. The A-P slope and angle of flexion is also indicatedin the GUI.

The pace of the rocking motion can be dictated by tracking grid 930. Thesurgeon will try to pace the movement of the knee joint back and forthto lead the needle shown in the GUI. For example, moving the knee jointto quickly will result in the needle not being able to follow the legmovement. The correct pace allows the needle to track movement of theknee joint. The knee joint movement should not move the needle outsideeither extreme. The sensored insert is taking quantitative measurementsover the arc to determine the position of Max G.

FIG. 12 illustrates a completed measurement of the tibia relative to themechanical axis of the leg. The knee joint has been rotated back andforth the predetermined number of times. Data points have been taken todetermine the maximum along the A-P line of the joint. The amount oftilt or slope on the tibial plateau can be calculated from the positionof the maximum. Tibia angle 152C is indicated on the GUI. A finalcalculation of tibia angle 152C can be indicated by changing the displaycolor and placing a box around the number. The GUI further indicateswhether the tibia angle is varus or valgus 152D relative to themechanical axis.

FIG. 13 illustrates a measurement of the femur of the leg relative tothe mechanical axis of the leg. The workflow of the system having nowcaptured the tibia offset to the mechanical axis now captures the bonetilt or slope of the distal end of the femur. In general, the differencein the leg alignment when compared to the mechanical axis is calculatedby subtracting the medial-lateral bone tilt of the distal end of thefemur from the medial-lateral bone tilt of the proximal end of thetibia. This difference is listed on the GUI underlying Mech. Axis (e.g.mechanical axis) based on the tibia and femur quantitative measurements.

In one embodiment, the leg is placed back in extension 620. The leg islifted in extension 620 such that the distal end of the femur is loadedby the knee joint. The leg in extension 620 is lifted until the sensoredinsert in the knee joint is at a 45 degree angle or an optimized angleas depicted on the GUI to the surface of the operating table.

The leg is lifted so the leg is pivoting 620 off of the femoral head ofthe femur. The leg is lifted such that the sensored insert in the kneejoint is at a chosen angle, for example approximately 45 degrees. In theexample, the numbers in the GUI under Mech. Axis will change color and abox is placed around the numbers when the sensored insert is about thechosen angle, for example in the 45 degree position. The surgeon 400 nowtakes the leg in the extended position 620 and moves the knee joint backand forth in the medial and lateral direction. This will allow thesystem to subtend the plane of the distal femoral implant or distalfemoral angle. As mentioned previously, the leg is pivoting off of thefemoral head of the femur when rocking back and forth.

In FIGS. 13 and 14, the leg is pivoted 1300 on the femoral head of thefemur. The knee joint is rocked back and forth and is tracked by thetracking grid on the GUI. The surgeon moves the leg at a pace that thetracking grid keeps up with the movement. Thus, the tracking grid limitsor controls how fast the surgeon moves the knee joint. The range of themovement is also limited by the tracking grid shown in the GUI. Thesurgeon limits the movement within the range of the tracking grid. Inone embodiment, the surgeon moves the knee joint back and forth toeither extreme of the tracking grid. The knee joint moves in an arc. Thesystem will measure and identify the Max G position of the sensoredinsert pivoted 1300 off of the femoral head of the femur and calculatethe tilt or slope of the medial-lateral distal end of the femur. Thetilt of the distal end of the femur is incorporated with the previouslymeasured tilt of the measured proximal end of the tibia to output anoffset relative to the mechanical axis as depicted in the GUI in 151Aand 151B. In one embodiment, the number can be changing as the leg isrotated back and forth. The varus-valgus angle is a measure of theoffset of the femur to the mechanical axis and corresponds to themeasured medial-lateral tilt of the distal end of the femur. Forexample, the femur is in alignment to the mechanical axis if the max Gposition corresponds to the A-P line. If the max G position is offsetfrom the A-P line then an offset exists relative to the M-L line of thedistal end of the femur that can be converted to a varus-valgus anglefor the femur. Thus, the varus-valgus offsets of the tibia and femurrelative to the mechanical axis is measured.

FIG. 15 illustrates a surgeon 400 rocking the leg in extended position,pivoting on the femoral head, and the Max-G is identified byaccelerometer measurements of the sensored insert such that themechanical axis offset 151C is boxed. The boxing of the Mech. Axis valueis an indication that the predetermined number of rotations has beencompleted and the offset value of relative to the mechanical axis hasbeen calculated. In the example, the mechanical axis offset is measuredas 0.8 degrees. This indicates that the distal end of the femur wasmeasured having a varus angle of 0.3 degrees. The combination of thetibia and femur offsets yields a value of 0.8 degrees from themechanical axis. In general, the measurement can be used to verify thatthe leg measures within a predetermined range of the mechanical axis.For example, there have been clinical studies that indicate that anoffset greater than 3 degrees can have significant issues with jointreliability. The surgeon can verify to a high degree of accuracy thatthe leg alignment is well within this limit. Moreover, as data is takenwith different bone geometries it may become standard to cut at specificoffsets for optimal fit and where which can be accomplished by using thesystem with a bone cutting jig as will be disclosed herein below. Thesurgeon can now evaluate the Total Knee Replacement (TKR) result as itrelates to alignment of the legs, alignment of the bony cuts, the softtissue tension and femoral-tibial implant congruity.

FIG. 16 illustrates a non-limiting example of a GUI that the surgeon canview which provides quantitative data, visualization, and feedback. Inone embodiment, the system can include a video recording of theprocedure. It illustrates a video 1600 of the surgeon manipulating theleg, a representation of a sensored insert 157, with associated angularreadings (e.g., CP Rotation, Mechanical Axis angle, Tibia angle, APangle, Flexion angle, and Tray rotation), and loadings.

FIGS. 17-34 illustrate a GUI software system in accordance to at leastone embodiment of the invention, which displays information that asurgeon can use during surgery. FIG. 17 illustrates a start screen whenthe software system is begun. The software system checks to make sureall devices (e.g., sensors) linked to the system are turned off. Ifthere are devices on, a message is displayed 1710 to notify the user toturn off the devices and will also indicate 1700 which device(s) aretransmitting data. The user is provided a button 1720 that can beselected for the software system to shut off devices for the user. Whenthe devices are off and not transmitting data, the system can initializeany new device that transmits data, search for devices, and remind 1800the user to activate the sensors if not detected (FIG. 18).

FIG. 19 illustrates the GUI system 100 after software activation andsensor detection. The GUI system 100 indicates a progress bar 1900showing the initializing of sensors (e.g., load sensors) a cancel buttonis provided 1910 to allow the user to stop the process. The GUI 100 cancontain multiple information, for example device type 140, device ID142, company 144, flexion 156, device, module, or prosthetic component157 (e.g., tibial insert), a signal indicator button 163, a zeroinginitiation button 164, a track button 165, a clear button 171, an alignbutton 166, a power indicator 169, a power on button 170, and severalother buttons that can be used for other features 167 and 168.

After initialization, the user is prompted 2000 to select a particularanatomical feature (e.g., left 2010 or right 2020 leg) that the sensorsare being used for (FIG. 20).

FIG. 21 illustrates the GUI 100 after initialization and featureselection. The user is prompted to zero the sensors (e.g. zero button164 turns red). In operation, during this stage, the prosthetic deviceis coupled to a reference surface. In one embodiment, the sensoredinsert is placed flat upon an operating room (OR) table and then a userselects the zero button 164 on the GUI to reference to the OR tablesurface. Once pressed the software zeros the offsets in the sensors. Asmentioned previously, the sensored insert utilizes at least a three-axisaccelerometer that is referenced to gravity to measure position, tilt,and rotation. When the zero button 164 is selected the GUI 100 notifies2200 the user that the sensor is being zeroed, and optionally provides abutton 2210 to allow cancellation of the zeroing by the user (FIG. 22).The zero button 164 can be deactivated (e.g., the text changes from redto black) when the notification 2200 is provided.

FIG. 23 illustrates the GUI 100 display when the zeroing process iscomplete. On GUI 100 a Tibial rotation 2300 is also displayed. In oneembodiment, tibial rotation 2300 corresponds to an amount of rotation ofa tibial tray of a tibial prosthetic component from a referenceposition. The sensored insert zero'd in the plane of the table can havea zero value for the x and y values. At this point the device (e.g.,implant 157) has not been placed in the anatomical feature (e.g., leg),and the loading 160 in the device shows 0.00 load values. After zeroingthe device the first time it can be rotated on the table about 180degrees and zeroed a second time for the new position. The softwaresystem can average the measurement values at the two positions,minimizing affect of the slope of the table. The x-y values have beenobtained for the accelerometer in the sensored insert (in the plane ofthe OR table). The device is then stood vertically and positionedagainst a plane perpendicular to the surface of the OR table to zero toa reference z-plane. In one embodiment, a reference block having az-plane surface is held against the surface of the OR table.Alternatively, a z-plane surface is available on the OR table. Afterobtaining the zero reference values in the x-y plane and the zdirection, the device/sensor can be translated into a sterile field(e.g., for operation).

Once moved to a sterile field, the tibia reference is captured, or thereference of the position of the tibia when the leg is in full extension(e.g., heel resting on table or leg holder). In the example, this is areference position selected by the surgeon that corresponds to the legin extension. This is done by resting the posterior edges 2310 of theimplant 157 along the tibial crest (see FIG. 4) or any other bonyprominence to define a plane. Tibial Rotation 2300 is used to measurethe angle of the tibial crest relative to the plane of the OR table.Thus, tibial rotation 2300 that is provided from the GUI is the tibiacrest reference angle and not the tray rotation in this measurement. Theuser can then click on the Flexion 156, where a blinking box 156Aappears, waiting for the user to now to rotate the implant 157vertically (in at least one embodiment within a range from −2 to 2degrees) while one contact remains on the tibial crest till the flexionangle is near zero.

A blinking box 156A becomes a solid line 156B box when the sensoredinsert is on the tibial crest and is approximately vertical. Tibialrotation 2300 of GUI 100 then displays the tibia crest angle. Theanatomical feature 162 of the femur and tibia are displayed in extensionwhen the tibia is at the measured tibia crest angle (FIG. 24). Note thatthe A-P (Anterior-Posterior) slope of the proximal end of the tibia orthe tibia plateau can be measured with the leg in extension. Themeasurement of the A-P slope is relative to the tibia crest. Note alsothat the tibia crest angle is roughly 2-3 degrees off of the mechanicalaxis of the tibia for a majority of patients. A shim can be coupled tothe sensored insert to adjust height. The sensored insert can be placedin the knee joint and coupled to the tibial tray of the tibialprosthetic component.

FIG. 24 illustrates the GUI 100 when the sensor module is placed in theanatomical feature. In the example, the sensor module is the sensoredinsert that is placed in the knee joint. The displayed sensor systemdisplays a value for the Tibia Rotation 2400, the load values (e.g.lbs.), and the center of load indicators are displayed (e.g., 158A and158B) also referred to as the contact points (CP). To zero the TibiaRotation a user can then click on the display of the Tibial Rotation2400. The zero location can correspond to a position designated by theuser that establishes a reference or starting position of the tibialprosthetic component. In one embodiment, the tibial tray of the tibalprosthetic component is aligned to a bone landmark or feature as astarting point. Alternatively, the insert can be rotated to apredetermined measured position and zeroed. When the sensored insert isplaced in the tibial prosthetic component the flexion value DD.D3represents the position in extension and the A-P slope of the tray inwhich the device has been inserted. In one embodiment, the A-P slope ofproximal end of the tibia bone cut at an angle from front to back. ThisA-P slope is measured by the accelerometer which changes the flexionvalue 156D from extension where the sensored insert may think the deviceis hyperextended. In general, a leg in extension should measure zerodegrees. The reading in box 156D is the amount of A-P slope measuredfrom the vertical. The user now selects or clicks on the lettering inGUI 100 for A-P 154D. The value in box 156C that corresponds to A-Pslope is transferred to box 154C or A-P slope 154D. The flexionmeasurement 156D transitions to a number near zero (FIG. 25), where theA-P value 154D is now the negative of the flexion value or −DD.D3, orpositive (since DD.D3 was negative). At this point the A-P value 154D ismeasured with respect to the tibia crest. The A-P value 154D can be usedto determine the slope of the tibial plateau bone cut. The measurementcan be used to verify that the cut is correct and corresponds to thecutting jig cutting angle for the tibia. Before the next stage ofalignment rotation values can be captured. The user can click on thelettering CP Rotation on the GUI 100.

FIG. 25 also illustrates the GUI 100 when the tibia rotation angle 2500is zero'd. When the Tibia rotation angle is zero'd, Contact Point (CP)Rotation angle 2510 is displayed. Note that the Tibia Rotation 2500 willstart to indicate values from zero. A positive CP rotation value is anexternal rotation (e.g., counter clockwise rotation on the page). Anexternal rotation is a rotation of the device toward the lateral side.The CP rotation angle 2510 is the angle a line through the lateralcontact point and the medial contact point makes with a horizontalplane, which is perpendicular to the OR Table (or floor). Thus, theimplant 157 image (e.g. sensored insert), illustrating a view lookingtoward the head from the knee, is rotated into the pagecounterclockwise, which would be a left leg lateral rotation (hencepositive CP rotation angle). As mentioned previously, the user canposition the tibial prosthetic component and the sensored insert in apredetermined location. The user can choose to zero at this referenceposition. Rotating the tibial prosthetic component and the sensoredinsert from this zero or reference position would be measured anddisplayed as CP rotation 2510.

FIG. 26 illustrates the GUI 100 when the surgeon balances out thecontact points. The surgeon, at full extension or any knee flexion angleof the limb, can try to balance the contact points on the two articularsurfaces of the sensored insert. The sensored insert has a plurality ofload sensors underlying the articular surfaces to measure load magnitudeand position of load. In one embodiment, the surgeon can pin the tibialprosthetic component to the tibia at a single point. This will allow thetibial prosthetic component to rotate or pivot the tibial tray andsensored insert. Rotating the tibial tray and sensored insert can changethe point of contact on the articular surfaces. The surgeon can use thistechnique to move the contact points closer to an optimum contactposition or within a predetermined range on each articular surface. Theamount of rotation to move the contact points is indicated in the tibialtray rotation box, the degree of parallelism of the contact points isdepicted as a degree representing the CP rotation value 2610. Subsequentmeasurements of the alignment to the mechanical axis will factor incontact point rotation in the calculations of bone alignment. In theexample, CP Rotation 2610 decreases and Tibial Rotation 2600 increasesas the device is rotated but note that a line passing through thecontact points is now more aligned with respect to the horizontal 2640of the display (e.g., the values of 158A and 158B are closer to eachother). In one embodiment, GUI 100 can indicate a predetermined arearange and compare the actual contact points to the predetermined arearange. The user would rotate the tibial tray and sensored insert untilthe contact points are within the predetermined region. Similarly, GUI100 can indicate a predetermined load magnitude range and compare to themeasurement of load magnitude on each articular surface. In one examplecontact points 158A and 158B are also not centered with respect to avertical line 2630 on the GUI 100, the surgeon can rotate to a non-zeroCP rotation value FF.F2 to get the contact points 158AA and 158B moresymmetric with respect to a vertical 2630 through the center of implant157.

FIG. 27 illustrates the GUI 100 when the surgeon clicks on the CProtation display to freeze the CP rotation value and the Tibia Rotationvalue in the software display. When the surgeon is satisfied with thelocation of the contact points he can click on the lettering “CPRotation” on the GUI 100, and boxes 2750 and 2760 (indicating the valuesare fixed) will appear near the Tibial (tray) Rotation Value 2700 andthe Cp Rotation Value 2710. The tibial (tray) rotation angle 2700 can beused for alignment. After this stage the alignment can begin, and theuser can click on the align button.

FIG. 28 illustrates the GUI 100 when the user (e.g. surgeon) clicks onthe alignment button 166 to initiate a measurement of muscular-skeletalalignment. In the example, the leg is measured and compared to amechanical axis with the prosthetic knee joint in place. The alignmentworkflow is started by indication on alignment button 166 when the“Align” lettering on button 166 turns red and a blue light on button 166turns on. A Tibia Plateau Slope value 152 is displayed and an indicatordial 2800 is displayed. In the example, the proximal end of the tibiahas been cut and the tibial prosthetic component is inserted and coupledto the tibia. The tibial plateau corresponds to the bone cut at theproximal end of the tibia. The tibial tray of the tibial prostheticcomponent couples to and takes on an angle of the bone cut on theproximal end of the tibia. Tibial Plateau Slope value 152 corresponds tothe medial-lateral slope of the bone cut on the proximal end of thetibia.

A needle indicator dial 2800 moves as the anatomical feature (withdevice 157) inserted therein (e.g. knee joint) is rocked back and forth.Note that rotation is related to the values of y/x, while tilt isrelated to the values of y/z. The device is rocked back and forth untilthe Max-Gx value is obtained, which should correspond to the y about 0if the internal (not displayed) tibia (tray) rotation is approximatelyzero. If the value is not zero at max A-P axis position, then there istilt. As mentioned previously, any CP Rotation value can be taken intoaccount for the calculation of Tibial Plateau Slope value 152. Duringalignment (referring to FIG. 26) the axis corresponding to the A-P ofthe device 157 is the vertical line 2630, while what is referred to asthe Medial-Lateral (ML) line is related to the horizontal line 2640, andthere is an axis perpendicular to both. Thus the rocking of theanatomical feature with the device 157 inserted, is essentially lookingfor the zenith of the arc of rotation, which should correspond to an MLline orientation that should be horizontal (about 0 degrees with respectto the horizontal on the GUI). If the angle is not zero, there ismedial-lateral slope cut into the proximal end of the tibia that ismeasured and compared to the cut angle set that was previously set intibial bone cutting jig. Thus, verification of the bone cut angle isachieved through quantitative measurement.

FIG. 29 illustrates GUI 100 feedback that is provided to the user whenthe leg is placed in flexion, for example 90 degrees (e.g., color offlexion angle text changes to yellow, indicator dial movement 2900, whenthe value is approached). Note that the value may be more than 90degrees due to the A-P slope of the proximal end of tibia bone cut. Ingeneral, the leg is placed in flexion whereby the device 157 is orientedat a predetermined (chosen) angle for example a 45 degree angle from thesurface of the OR table. Note that if the device 157 can be oriented at45 degrees with respect to the plane of the OR table, the orientation ofthe A-P line and the normal to the A-P and M-L lines are both about 45degrees or roughly equal in value with respect to gravity.

The knee in flexion is displayed 162 in the GUI 100. The amount the legis in flexion is listed under Flexion 156 of GUI 100. Display allows thesurgeon to rapidly assimilate the leg position at a glance. In oneembodiment, the tibia is pivoted on a point of the mechanical axis. Forexample, the surgeon holds the heel down at the table with one handallowing the heel to be a pivot point (see discussion above for FIGS. 9and 10). With the other hand under the knee joint the surgeon moves theknee joint inward and outward (while pivoting about the heel contact.The patient remains in a fixed position during the movement. As thesurgeon moves the knee joint in and out on the pivot point the indicatordial 2900 moves and follows the motion. A delayed response of the dial2900 with the motion indicates that the motion is too fast, and alsoprovides feedback as to the rotation angle. Data is being taken todetermine the zenith values, which will determine the tilt values.Multiple rocking past and forth about zenith is done to take data pointsalong each complete arc and then the points from each arc are used todetermine the location of the zenith. As the surgeon rotates the kneejoint and pivots on the heel the indicator dial 3000 (FIG. 30) alsomoves to the side of rotation. For example, FIG. 30 illustrates the casewhere the surgeon has pivoted the knee joint counterclockwise (asmeasured on the display). If during the rotation an error occurs, thesensor module can force the surgeon to start the flexion motion again.Similarly, if the heel inadvertently moves during motion, and theflexion values 156 moves away from the target, the indication of beingclose to the target position (e.g., yellow text angle) can disappear(e.g., change back to a non close indicator color such as white).

FIG. 31 illustrates the GUI 100 when the surgeon has gone back and fortha predetermined number of times while pivoting on the heel of the legsuch that the conditions for measurement have been met. The MechanicalAxis (HKA 150) (also referred to as the load bearing axis) alignmentnumber is now displayed and frozen, as is the Tibia Plateau Slope 152.The HKA or mechanical axis 150 of the display is a measure of the totaloffset of the femur and tibia to the mechanical axis. There is clinicalevidence that indicates that misalignment of a prosthetic joint to themechanical axis above a predetermined amount will result in jointperformance loss and long-term reliability issues. Moreover, asprosthetic component design becomes more sophisticated surgeons can addpredetermined slopes to the bone cuts to enhance performance. The systemcan be used to verify the angle of the bone cuts and the trialprosthesis. Thus, a measurement of the tibia alignment to the mechanicalaxis has been measured. GUI 100 will display an offset in degrees thatis either varus or valgus to the mechanical axis.

FIG. 32 illustrates the GUI 100 when the surgeon begins to measure anoffset of the femur to the mechanical axis. In one embodiment, the legis placed in full extension and lifted to pivot on the femoral head ofthe femur in the hip joint. The surgeon lifts the leg in full extension3200 at an angle 3210 that places the sensored insert in the knee jointat approximately 45 degrees to the surface of the OR table. In oneembodiment, mechanical axis value 150 disappears from GUI 100 as thefemur offset is being measured.

FIG. 33 illustrates that as the surgeon gets close to the targetposition, feedback is provided (e.g., the text of the flexion angle 156changes, referred to as device color). For example if the target is −45degrees the color of the text will change when the sensored insert angleapproaches −45 degrees within +/− a few degrees in the knee joint. Thus,the femoral offset to the mechanical axis can be measured upon reachingthe appropriate angle for the sensored insert (e.g., −45 degrees) withthe leg in extension.

With the leg in extension (see FIG. 28) the knee joint is then rotatedback and forth pivoting on the hip joint a predetermined number oftimes. Similar to the measure of the tibia offset, data points aremeasured over each arc created by the knee joint and the data points areused to determine a zenith or Max G of the arc. The position of the MaxG of the arc of the knee joint is used to calculate the medial-lateralslope of the distal end of the femur surface. The femoral offset ismeasured in degrees and can be varus or valgus to the mechanical axis ofthe leg. GUI 100 displays the combined offsets of the tibia and femur tothe mechanical axis. In one embodiment, the measured femurmedial-lateral slope is subtracted from the tibia medial-lateral slopevalues to obtain an offset value 3280 that is displayed in mechanicalaxis 3270. Once a measured value average is obtained the color of thetext in mechanical axis 3270 changes to match the text of the otherindicators (e.g., A-P) and a box 3290 appears around the offset value3280 in mechanical axis mechanical axis 3270. The angular accuracyobtained by at least one embodiment is on the order of 0.5 degrees fornavigation and at least one embodiment can obtain greater than 0.1degree accuracy.

In FIG. 34, the GUI 100 displays when the surgeon repositions the leg toobtain a new target flexion angle value. In one embodiment, a HKA ormechanical axis value 150C disappears, while maintaining again themeasured Tibia value 152. In this example the knee position 162Balignment target is a flexion angle 156 of 45 degrees. As the surgeon isapproaching the target flexion (e.g., 45 degrees also referred to as amid flexion target) feedback is provided, for example the flexion angletext 156 changes to a device color. If the surgeon has moved outside thetarget flexion value the indicator text color changes. When the surgeonis back within the target window about the third flexion target angle(e.g., 45 degrees), the text displays the angle in the device color.

The discussion above is for a non-limiting embodiment that discusses thealignment of a device (sensor) 157 placed into an implant. Note that thesensor 157 can also be placed into a cutting jig 3530. The cutting jig3530 (FIG. 35) is coupled to the bone, as described below to define oneor more bone cut angles. The device 157 can be used to align cutting jig3530 to precisely cut bone angles relative to the mechanical axis. It isused similarly as described hereinabove to measure femur and tibiaoffset to the mechanical axis. The measurements can then be taken intoaccount in aligning cutting jig 3530 to specific bone cuts. Thus, bonecuts can be made using quantitative measurements using a conventionalbone cutting jig in conjunction with the system disclosed herein.

In one embodiment, device 157 is a sensored insert. A shim can becoupled to the sensored insert. The shim can have a tab extending fromthe shim body that couples into a cutting slot of cutting jig 3530.Alternate variations can also be used to affix the sensored insert andshim to the cutting jig 3530. Cutting jig 3530 is attached to a bone.FIG. 35 illustrates bone cutting jig 3530 coupled to the tibia of theleg. The sensored insert is referenced as disclosed above prior tocoupling the sensored insert to bone jig 3530. For example, the device157 can be zeroed to a plane of the operating table. Similarly, device157 is zeroed to a plane perpendicular to the operating table. The legis then placed in an approximate position of extension. The insert iscoupled to a bone landmark or tool coupled to the leg. For example, thedistal end of device 157 is held against and referenced to the tibialcrest as disclosed above. In another fashion, the jig can be inserted inthe knee with the attached sensor, and the pre-cut slope of the proximaltibia plateau can be referenced.

Once referenced, device 157 can be coupled to a cutting jig to measurealignment. Cutting jigs are typically coupled and aligned to a bone in apredetermined manner identified by the manufacturer of the jig. The jigcan have a cutting slot for fitting a saw to cut the bone at a preciseangle. The cutting slot of the cutting jig can be precisely moved tochange the angle of the cut from a reference position of the jig. In oneembodiment, cutting jig 3530 coupled to the tibia is referenced to makea cut with zero medial-lateral slope and zero anterior-posterior slopeto the proximal end of the tibia. The cut can be a simple cut along asingle plane or a compound bone cut across multiple planes. The shimthat couples to the bone jig can be customized for fitting a specificjig. The manufacture of the shim has a substantially lower cost thandevice 157. This allows device 157 to be used for a wide variety ofdifferent jigs and prosthetic components without costly modification.

In one embodiment, the shim couples device 157 to bone cutting jig 3530such that device 157 is in alignment to the cut to be made in the tibia.As mentioned previously, the device has been zeroed and referencedsimilar to the example when the sensored insert is installed in the kneejoint to verify alignment and bone cuts. The process of measuring thealignment of the tibia relative to the mechanical axis and the femurrelative to the mechanical axis is also similar to that disclosed abovefor the sensored insert in the knee joint. The leg is placed in flexionsuch that device 157 is at a 45 degree angle to the surface of theoperating table. The heel of the leg is held against the operating tablewhile device 157 is positioned. The heel is held at the position wheredevice 157 is at a chosen angle, for example a 45 degree angle as apivot point for the knee joint. The knee joint is rocked back and forthpivoting off of the heel. The ankle can be held to prevent movement inrelation to the heel. The system measures points of the arc as the kneejoint is rocked back and forth (see discussion with respect to FIG. 28).The knee joint is rocked back and forth a predetermined number of times.The system calculates the location of the Max-G point of the arc. Thesystem then calculates the medial-lateral slope of the proximal end ofthe tibia from the location of the measured Max-G position relative tothe Max-G position for the tibia aligned to the mechanical axis. Thecalculated medial-lateral slope corresponds to a varus or valgus offsetor angle of the tibia relative to the mechanical axis. The surgeonutilizes the quantitative measurements to adjust bone cutting jig 3530to set appropriate bone cut angles for A-P slope and M-L slope takinginto account the patient anatomy and the specific prosthetic componentsbeing used. The tibial prosthetic component can be installed after thebone cut has been made and angles re-checked.

FIG. 36 illustrates two bone cutting jigs that are used on opposingbones (e.g. femur and tibia) of a muscular-skeletal joint. In theexample, jig 3530 is coupled to a proximal end of the tibia and a jig3630 is coupled to a distal end of a femur. Device 157 can be coupled toeither cutting jig as disclosed above. Although disclosed hereinabove,the system provides the option of cutting the femur or the tibia first.The A-P slope can be captured. Note the process is similar to thatdescribed above, for example the 90 degree bent knee can now be rockedmultiple times except the movement is to obtain a near zero value of thetibia angle 3510. When the user has a tibia angle close to zero thetibia select button 3540 is pressed to switch to the femur, and the jigon the tibia is locked in place. The process is then repeated for thefemur jig 3630, see FIG. 36, where the femur select button is showing3640, and the object is to zero the femur value 3610. Now the distalfemur and proximal tibia can be cut.

Additionally the device can be placed on the tibia plateau of a cutdistal face. The sensor can be pinched in place until the loading iseven, and used to mark aligned drill holes to place a cutting jig.

As described above at least one embodiment can be used to make bonecuts. Herein we described a non-limiting example of an embodiment usedto cut bones for installation of a prosthetic knee joint, although theembodiment is not limited to any particular joint or bone. The systemcan be used to make any bone cuts of the muscular-skeletal system. Inthis description the assumption is that a user has launched orre-launched the GUI as disclosed hereinabove. The GUI can providefeedback for zeroing the device. In at least one embodiment zeroing thedevice will include a flat (horizontal) orientation with respect to asurface (e.g., table), and a vertical orientation with respect to thesurface of the table. Feedback may include a tone, and/or text on theGUI, for example the GUI may display the text “Please rotate the device180 degrees and re-position it flat on the table—press the “Zero” buttonagain.”

FIG. 37 illustrates the bones of a knee 3720 and a device 3700 (e.g.,insert sensor), where the device 3700 is placed flat 3730 (e.g., aboutparallel with the surface of the table) upon the table 3710 for zeroing.The feedback will then instruct the user to move the device 3700 into avertical orientation for zeroing. For example the GUI may display thetext “Please position the device vertically—press the “Zero” buttonagain”. Device 3700 includes a plurality of sensors for measuring aparameter of the muscular-skeletal system. Device 3700 can be in theform of a prosthetic component for trial or permanent measurements. Inthe example, device 3700 is a sensored insert having a plurality of loadsensors underlying each articular surface and at least one 3 axisaccelerometer for measuring position, rotation, and slope (or tilt).

FIG. 38 illustrates the bones of a knee 3720 and a device 3700 (e.g.,insert sensor), where the device 3700 is placed vertical 3740 (e.g.,about perpendicular with the surface of the table) upon the table 3710for zeroing. Once the device is zero'd the GUI can indicate that to theuser (e.g., via text) and the device can be moved into the sterilefield. Note that the zeroing can be done on a back table and transferredinto the sterile field.

Once zero'd the device can capture the tibia in a reference position asdescribed above. For example, the leg is positioned in extension orapproximately in extension. The same technique as described above can beused to capture a bone landmark such as the tibia crest (FIG. 39). Thedevice 3700 is placed on the tibia crest (note here the bone is showing,whereas in actual practice the device can be place upon the skin abovethe tibia) resulting in an axis 3910 running through the bisector axis(same axis as the vertical axis in FIG. 38 when zero'd vertically),where the axis 3910 is approximately perpendicular with respect to theplane of the surface of the table. Once the reference position iscaptured the GUI may provide feedback, for example the GUI may displaythe text “The Reference captured”. Place the device in tibial prostheticcomponent tray“. In extension, click A-P indicator to capture A-Pslope”.

Once the tibia crest is captured and the leg is in full extension, acutting jig, either individually or in relation to each other can becoupled to the bones for cutting bone surfaces at precise angles forreceiving prosthetic components. The process for finding alignmentrelative to the mechanical axis can similarly be identified as disclosedherein above only with device 3700 coupled to a bone cutting jig. Thesupports precut alignment of the cutting jigs to the mechanical axis. Inthe non-limiting knee example the proximal tibia and the distal femurcan be cut. The cutting jig can be a commercial jig and need not be aspecialized cutting jig when using the techniques described herein andan adapter to couple device 3700 to the commercial jig.

FIG. 40 illustrates at least one example of a method of connecting thedevice 3700 to the cutting jig 4200 via an adapter 4000. Adapter 4000can be a low cost shim that couples to device 3700. In one embodiment,adapter 4000 has a tab or tongue that extends from the shim body. Thetab of shim 4000 fits into a cutting slot of a cutting block. In theexample, different adapters can be made for different cutting blocksallowing easy adaptability to various prosthetic component systems.

FIG. 41 illustrates the combined device 4100 including the adapter 4000and the device 3700. In one embodiment, adapter 4000 and device 3700have corresponding features that couples adapter 4000 to device 3700. Inthe example, the features allow adapter 4000 to be removed from device3700. For example, adapter 4000 can have corresponding lips or flangesthat couple together by interference or by connector.

FIG. 42 illustrates the insertion of the combined device 4100 into acutting jig 4200 that is capable of accepting the combined device 4100,forming a cutting system 4300. The tab extending from the adapter 4000fits into a receiving portion 4215 of cutting jig 4200. In the example,receiving portion 4215 of cutting jig 4200 is a cutting slot. The tabfits into the slot and is retained by cutting jig 4200. The tab alsomaintains an alignment of device 3700 to cutting jig 4200.

FIG. 43 illustrates the device 3700, adapter 4000 and cutting jig 4200coupled together. The cutting system 4300 can now use the alignmentinformation of the device 3700 to reference bone cuts. The tab ofadapter 4000 is inserted into receiving portion 4215 of cutting jig 4200to retain and align device 3700 to cutting jig 4200. In one embodiment,the posterior portion of device 3700 couples to a surface of bonecutting jig 4200.

FIG. 44 illustrates the cutting system 4300 coupled to the extended leg.In the example, system 4300 is coupled to the tibia in preparation ofcutting the proximal end of the tibia to receive a tibial prostheticcomponent. As mentioned previously, system 4300 was referenced to atibia reference (e.g. tibial crest). System 4300 will measure the A-Pslope of the bone cut with the leg in extension. The bone cutting jigcan be adjusted to change or modify the A-P slope of the bone cut.

The leg is then placed in flexion (FIG. 45) where a plane defined by thejoint passes through about a vertical 4500. The position of flexion isselected where the accelerometer in system 4300 is at a 45 degree angleto the referenced surface (e.g. the operating table). The heel of theleg is held at the position achieving the 45 degree angle. As previouslydescribed above the joint 3720 can be rocked back and forth 4510 withthe cutting system 4300 on the joint as it is rocked. The knee joint ispivoting on the heel of the leg. System 4300 measures the Max-G of thearc created by the rocking motion. The position of the Max-G inconjunction with the leg anatomy is converted to a measurement of thetibia offset.

Using the measurement information the cutting system 4300 can adjusted4520 to change or modify the vargus and valgus tilt of the proximal endof the tibia. In one embodiment, system 4300 is fastened to bone withbone screws prior to measurements being taken. System 4300 can have anadjustable cutting slot thereon that can change or modify the A-P slopeand M-L slope of the jig. In a second embodiment, system 4300 can bepartially fastened to bone allowing the jig and thereby the cutting slotto be moved and pinned for the bone cut after the measurements have beentaken and adjustments made. In a third embodiment, system 4300 can betemporarily fastened to the bone allowing the measurements to be made.The cutting jig can be adjusted after measurements have been made to cutthe appropriate bone slopes. The cutting jig can then be fastened tobone prior to making bone cuts with a bone saw.

As mentioned previously, since cutting system 4300 is referenced to thetibia reference an A-P slope can be obtained. For example FIG. 46illustrates an extended joint where the cutting system 4300 cutting slotis moved 4620 to obtain a desired A-P slope. Note that the illustrationin FIG. 46 shows cutting system 4300 on the tibia, however the sameprocess as described above can be used on the femur. For example insteadof the A-P slope one would obtain the distal-femur flexion angle.

FIG. 47 illustrates a bone cutting system 4700 on a distal end of afemur and a bone cutting system 4300 on a proximal end of the tibia.Moreover, measurements can be taken on the femur and the tibia to adjustcutting systems 4300 and 4700 to achieve parallel bone cuts. In oneembodiment, the measurement device is moved from the system 4300 tosystem 4700 or vice versa to take measurements. The leg is placed inextension and verified by systems 4300 or 4700 depending upon which hasthe measuring device. For example, system 4300 is coupled to theproximal end of the tibia, the tibia measurement is selected on the GUI,the A-P slope of the proximal end of the tibia is measured, and the A-Pslope of system 4300 is adjusted for cutting a predetermined A-P slope.Similarly, the measuring device can be transferred to system 4700.System 4700 is coupled to the distal end of the femur, the distal femurflexion (e.g. A-P slope) is measured at the distal end of the femur withthe leg in extension, and the distal femur flexion is adjusted forcutting a predetermined A-P slope. In one embodiment, the bone cuts onthe distal end of the femur and the proximal end of the tibia are set onthe cutting blocks to be parallel to one another. This can be done veryaccurately because the bone cut settings use quantitative measurementsfrom the measurement device referenced to the same plane.

The offset of the femur and tibia relative to the mechanical axis isalso measured with systems 4300 and 4700. The femur and the tibia arerespectively pivoted on the femoral head and the heel of the leg asdisclosed herein. Data points are taken over several arcs as the kneejoint is rocked back and forth a predetermined number of times. TheMax-G point is located for the tibia pivoting on the heel and avarus-valgus offset is calculated. Similarly, the Max-G point is locatedfor the femur pivoting on the femoral head of the femur and avarus-valgus offset is calculated. The information can be used to adjustthe medial-lateral slope of the bone cut for the distal end of the femurand the proximal end of the tibia.

Thus, two cutting systems 4300 and 4700 can be used to get the desireddistal femur flexion angle 4720 for the femur cutting system 4700 andthe desired A-P angle 4620 for the tibia cutting system 4300, whileorienting the cutting systems 4300 and 4700 so that they are parallel.Furthermore, systems 4300 and 4700 can measure the vargus/valgus tiltrelative to the mechanical axis for the femur and tibia. The surgeon canuse the measurement data from systems 4300 and 4700 to set themedial-lateral bone cuts on respectively the proximal tibia and distalfemur. Note that as described above the vargus/valgus are measured withrespect to the mechanical axis, where the mechanical axis is not theanatomical. The cutting systems 4300 and 4700 are coupled to the distalfemur and the proximal tibia with the adjusted cutting slots based onquantitative measurements. A bone cutting saw is then used to but thefemur and tibia. Note that both cutting systems 4300 and 4700 can bealigned with regards to any axis. In the embodiment described bothcutting systems 4300 and 4700 were aligned to the tibia crest, thusultimately to an axis of the tibia, however one could choose a femuraxis to reference as well.

In addition to making initial cuts one can use the system to makeadditional cuts. For example the lateral femoral condyle can roll backon the tibia plateau causing unwanted lifting on the lateral sidethereby placing all or most of the loading on the medial condyle as theknee is placed in flexion. The cutting jig is typically placed back onthe distal femur, which already has a first cut. Occasionally, a secondcut is made to adjust the angle of the femoral insert/component bycutting the posterior condials of the distal femur. The second cut ismade by a special cutting jig that has some cut rotation built into thecut to compensate for the lift off in flexion. At least one embodimentcan be used to increase the accuracy of the second cut. For example afemural rotation guide can be placed upon the first cut with a deviceinserted to orient a cutting jig optimally for the second cut.

FIG. 48 illustrates a femoral rotation guide 4800 where two condialsurfaces 4840A and 4840B can pivot 4860 about an axis 4850 when pinchers4810A and 4810B are squeezed or extended away from each other 4820. Thecondyle surfaces 4840A and 4840B are placed upon the cut condyles of thedistal femur, and attached to the posterior uncut condyles of the femur.Note that the femoral rotation guide 4800 can be inserted with thepatella reduced to provide realistic loading, and information regardingpatellar tracking while rotational adjustments are made. At least onereference hole 4870 is available so that once the correct orientation isobtained. Reference holes for the cutting jig can be drilled into thebone. The femoral rotation guide 4800 can be removed and a cutting jigplaced on the bone to be cut at an optimal rotation that supports bothcondyles contacting each articular surface over a range of motion of theknee joint. The cutting jig is lined up with the reference holes andscrews inserted therein to fasten the device down.

FIG. 49 illustrates the femoral rotation guide 4800 attached to thedistal end of the femur 4900, with the device 3700 inserted into atibial tray 4910 or placed on the tibia plateau cut. The assembledcomponents allow the leg to be moved through the range of motion. It isimportant to note, that the patella 4920 is moved in-place and theloading observed, rotating the knee joint to determine if condylesurfaces 4840A and 4840B are loading device 3700 over the range ofmotion (e.g., load sensor tibial insert). Note that FIG. 49 shows thesystem in separated view however when measuring the loads the condylesurfaces 4840A and 4840B will be in contact with device 3700. In oneembodiment, after the proximal tibia and distal femur are cut, the legis taken into extension. By knowing that the condylar geometry of thejig is the same as the distal femur, and the tibial sensor has the samegeometry as the tibial component, the knee is extended and rotation ofthe femoral and tibial jigs can optimize implant congruency inextension, then soft tissue balancing can be performed to balance the“extension gap”. The leg is now placed in flexion and pinchers 4810A and4810B are squeezed together such that posterior femoral condyles 4840Aand 4840B shift, translate or rotate to engage the condyles of thecorresponding Tibial articular surface. The loading can be viewed on theGUI. When the loading on both articular surfaces of device 3700 are atan appropriate level or within a predetermined load range then dial 4830is used to lock the pinchers so that the rotation 4860 is locked, and APtranslation defined. Reference holes 4870 can then be drilled forsubsequently mounting the cutting jig. Thus in summary, the pinchers4810A and 4810B are pinched 4820 resulting in rotation 4860 of thecondyle surfaces 4840A and 4840B thereby changing the loading measuredby the device 3700. The angular orientation of the femoral rotationguide 4800 is locked and the reference hole drilled when a correctloading over the range of motion has been found. This process can beperformed having all the muscular-skeletal joint anatomy in-place forcorrect kinetic loading. The cutting jig can then be aligned with thedrilled reference holes and used to make the chamfer cuts and A-P cuts.Note that in this embodiment the femoral rotation guide can be adisposable system, and used to measure loading with the patella in placemoving the leg in flexion and/or extension.

At least one embodiment is directed to a novel sensor system thatincorporates positional sensing, load sensing, RF communications,powering and telemetry in a footprint of a tibial trial. This footprintis miniaturized to allow incorporation of the trial insert into otherinstruments that are utilized during a knee procedure such as gapbalancers, distractors, and cutting jigs or can be molded to fit intoany orthopedic system (e.g., knee system). The sensor system can also beplaced in the tibial prosthetic component or the femoral prostheticcomponent. Furthermore, the design is not limited to measurement andalignment of the knee but can be used for hip, spine, ankle, shoulder,elbow, hand, wrist, foot, bone, and the muscular-skeletal system. Notethat the sensors used in the sensor system are not limited to anyparticular type of sensor for example the sensor(s) can be capacitive,ultrasonic, film sensing, accelerometers, inclinometers, gyroscopes,acoustic, and electromagnetic.

At least one embodiment is also directed to a sensor system thatcommunicates intra-operatively with real time data to a GUI that can beinterpreted by the surgeon. This GUI can represent data from thesensors, can be voice activated and controlled, can integrate other datafor display such as IR/US navigation systems for incorporated datapoints. Can record surgical footage with time stamped sensor data, canincorporate data related to the patients pre-op/intra-op/ and post-opdata. Implant data can be captured, which can be sent to a cloudcomputing system for access. At least one embodiment is directed to asensored system composed of a trial insert that: can be used as astandard trial with no utilization of the electronics; can be utilizedprior to cutting the bone to give angular/positional information ofproposed cut angles; can be utilized after the cuttings jigs areattached to the femur and tibia to confirm appropriated angularpositioning for the cut; can be utilized after the bony cuts have beenmade to check the accuracy of the angular cuts; can obtain a plane (suchas the tibial crest) which the sensors can now reference to, to providean angular number for interpretation to reference to before or after acut is made; can incorporate other data points from other instruments(IR/US/Magnetic) on the GUI to incorporate information forinterpretation; can incorporate angular information and load informationwith the knee implant trials in, which can allow the surgeon to refinethe angular cuts and/or soft tissue balance, and/or implant position androtation real time to optimize the leg alignment as defined by thesurgeon; can give real time data as to how angular geometry of the bonycuts/angles or the implant geometry affects soft tissue balance/loadsand implant kinetic function; can give real time data as to how the softtissue tension affects the overall mechanical alignment of the leg, andthe implant kinetic function; can give real time data as to howadjustments to the bony angles and soft tissue tension affect each otherin a dynamic function and affect collectively or independently thekinetic knee function; can be used with a trial implant system or afinal implant system prior to closing the joint; can utilize a referenceangle/plane that can be changed intra-operatively at the discretion ofthe surgeon; can give information related to implant congruency,alignment and soft tissue balance with thicker trial inserts, and/orangular insert change; and can utilize incorporation of pre-operativescans such as x-rays, CT scans, MRI's into the GUI to reference intra-opplanes and angles to. The Tibial and or Femoral cuts can be made first,then the Secondary femoral or Tibial cut can be made by knowing theangular reference of the interposed cutting jig to obtain equalextension gaps and flexion gaps. It allows distance gap measurements toincorporated soft tissue tension in multiple knee angles.

In addition to utilizing the sensor 3700 on the tibia crest 427, atleast one embodiment 5000 (e.g., reference position tool), FIG. 50,utilizes a sensor 3700 on a tibial alignment device/tool 5010 to obtainthe alignment information discussed herein with reference to FIGS. 4 and39, where the alignment device 5010 and the sensor 3700 move as one asdid the sensor 425 on the tibial crest 427 in FIG. 4. For example thetool 5010 (with sensor 3700 attached) is rotated back and forth in thesame manner as the device 3700 on the tibial crest to obtain alignmentinformation as in the discussion with reference to FIGS. 4 and 39. Inthis particular embodiment the sensor 3700 and alignment device 5010move together, where the alignment device 5010 is positioned so that oneend 5025A is approximately aligned 5010A with the proximal end 5020 ofthe tibia. The opposite end 5025B of the alignment device 5010 isapproximately aligned with the distal end 5010B of the tibia 5030.

FIG. 51 illustrates a different view of the device shown in FIG. 50. Thealignment device 5010 is extendable so that the ends 5010A and 5010B aremoveable to fit any leg or the tool/alignment device 5010 can comprisemore than one tool having several different lengths. At least oneembodiment is adjustable to any length needed for example FIG. 51illustrates an adjustable 5040 alignment device 5010. For example thesection 5010 D can be attached to a slightly smaller bar 5010E thatslides into a slightly large similarly shaped channel 5010F. Thealignment device 5010 can be manufactured out of many different types ofmedical grade material (e.g., stainless steel, bio-compatible plastic).The alignment device 5010 can include an arm 5025 that contacts with therelative positions 5010B and 5010A where the arm 5025 extends from thebody 5012. Note that the sensored device 3700 can be a prostheticcomponent.

At least one embodiment is directed to a muscular-skeletal alignmentsystem 5000, that includes: a sensored device 3700 including at leastone 3-axis accelerometer for measuring position, rotation, and slope; aremote system 5090, coupled to the device (e.g., wired or wirelessly5095) for receiving position, rotation, or slope data; and a tool (e.g.,alignment device 5010) configured to couple to the muscular-skeletalsystem where the tool is configured to be positioned to generate areference with the sensored device 3700 coupled thereto. Thetool/alignment device 5010 can include a tab 5031 so that the sensoreddevice 3700 can be inserted onto the tool/alignment device 5010 and thesensored device 3700 can include a slot to accept the tab 5031.

FIG. 91 illustrates one possible configuration of axes with sensoreddevice 3700, where the initial orientation of the sensored device 3700lies in the x-y plane, and the z-axis is normal to the x-y axis inaccordance with the right-hand rule. For example where the body axes ofthe sensored device 3700 (x-s, y-s, z-s) initially are aligned with thereference axes (x, y, z). When the sensored device is then moved out ofalignment with the reference axes (x, y, z) the orientation of thesensored device body axes (x-s, y-s, and z-s, can be projected onto thereference axes (x, y, and z) to obtain Dx, Dy, and Dz. These in turn canbe used to define tray rotation, varus, valgus, flexion and slope. Forexample tray rotation can be defined as arctan(Dy/Dx), Varus and Valguscan be defined as arctan(Dy/Dz), and Flexion and Slope can be defined asarctan(Dz/Dx.).

FIG. 92 illustrates a plot of the x-acceleration value (e.g., obtainedby an accelerometer) versus angle of inclination θ. As can be seen thereis a region of linearity 9100, valid within a range of acceleration(e.g., −0.8 to 0.8 g) and angle of inclination (−45 degrees to +45degrees). The angle of inclination can be defined as the inverse tangentof the ratio of (axout/ayout) or the ratio of the x acceleration valueto the y acceleration value.

FIG. 93 illustrates a bent leg (sometimes referred to as a bent knee),with a sensor 9315 oriented at an angle, for example 45 degrees withrespect to axis of rotation 9370A. Note other references can be used todefine the angles of sensors. The knee/leg can be defined by the femuraxis 9310A and 9310B, and tibia axis 9320A and 9320B. The knee can berotated about the hip center 9330 and the “virtual” pivot point 9340 toobtain the mechanical axis 9300. Intersection of the two planes 9380 and9390 defines the axis of rotation, which is along the load bearing,mechanical axis 9300. Plane 9380 is defined by femur axis 9310B andtibia axis 9320B, plane 9390 is defined by femur axis 9310A and tibiaaxis 9320A. The femur axis (9310A and 9310B) is offset 9360 with respectto the hip center 9330. The rotation moves the knee middle 9371 from9370A to 9370B equivalent to the plane 9390 rotating to position 9380.One of the pivot points of the leg is the heel 9345, while the femuraxis (9320 A and 9320B) passes through the center of the ankle 9350A and9350B respectively to the “Virtual Pivot” 9340 that falls in line withthe Heel 9345 and Hip Center 9330, defining the Axis of Rotation 9300.Note that the virtual pivot 9340 can lie above or below the plane 9342(e.g. table).

To obtain the mechanical axis (MA) the Tibia-V is obtained by rotationon hip center 9330 and heel 9345 and capturing the a y/z value at themaximum x-value (e.g., maximum of the arc), as measured by the sensor9315. The distal Femur-V value is obtained by lifting the leg inextension to a position where a sensor in the knee is upside down butstill at 45 degrees, and rotating on the hip center 9330 to capture anew y/z value at the maximum x value as measured by the sensor 9315.Then the Mechanical axis can be defined as MA=(Tibia-V)−(DistalFemur-V).

FIGS. 94A and 94B illustrate two positions that can be used to average xand y positions to minimize error in the x-y reference plane. Forexample, a sensor 3700 can lie on a table 9400 and be rotated (from FIG.94A to 94B). FIG. 95 illustrates a vertical position (of sensor 3700 x-saxis with table 9400) that can be used to average y again to minimizeerrors (e.g., internal assembly position of the accelerometer) and toaverage z.

Thus as discussed, one can calculate alignment to the mechanical axis byrotating back and forth on the pivot points. Note that the sampling rateof the sensor can vary for example a sample rate at 15 times/second whengetting data points on the arc can be used. As discussed depending onthe position of the max X (maximum of the arc) one can identify the tilt(Y/Z) of the bone cut (medial/lateral) which corresponds to theVarus/Valgus of the bone to the mechanical axis. Note that rotation backand forth can continue until one get measurements that are within a ½degree of the average.

FIG. 90 illustrates at least one embodiment that is directed to a method9000 of generating a reference position comprising the steps of: 9005coupling a device 3070 having a three-axis accelerometer to a referenceposition tool 5010; 9010 placing a muscular-skeletal system in apredetermined position; 9020 positioning the reference position tool5010 to at least one muscular-skeletal landmark of the muscular-skeletalsystem; 9030 aligning one plane (e.g., 5010A or 5010B) of the devicewithin a predetermined alignment range; and 9040 measuring a position,rotation, or tilt of the reference position tool at the predeterminedposition. A further embodiment includes a step 9050 of adjusting alength (e.g., 5040) of a body of the reference position tool. A furtherembodiment includes 9060 clipping the device to a body of the referenceposition tool. A further embodiment includes a step 9070 of contactingthe muscular-skeletal system with a first and second arm of thereference position tool where the first and second arms extend from abody of the reference position tool.

Note that the non-limiting description describing aspects of theinvention for use in a total knee replacement (TKA) surgery, theinvention is not limited to TKA but can be used in orthopedic surgery ingeneral or for any joint repair, spine surgery, bone, or portions of themuscular-skeletal system that incorporates bony cuts and soft tissuebalance for an optimized outcome, with or without implants.

Additional Embodiments

Additional non-limiting examples of embodiments will be discussedherein.

FIG. 52 illustrates at least one embodiment 5299 is directed to methodsand devices using kinetic measurements for joint alignment. For exampleat least one embodiment 5200 is directed to a method of measuring jointalignment between first (e.g., femur) and second bones (e.g., tibia)comprising the steps of: positioning a joint to a target flexion value(e.g. a chosen knee bent) as measured by a sensored module within thejoint 5210; rotating the joint 5220 between a first point and a secondpoint where the first and second points are on opposing sides of thejoint 5220. For example referring to FIG. 1A the first point can bealong path 102A, while the second point is along 101A and the act ofrotating is moving along the paths 101A and 102A. For example, asdisplayed in FIG. 53, 5310 the first point can be about 45 degreesmedially along 101A measured with respect to the vertical axis 100A,while the second point can be about 45 degrees laterally along 102Ameasured with respect to the vertical axis 100A. A first alignment valueis saved 5230, where the first alignment value is related to theposition of the first bone, for example the first alignment value can bethe angular relationship between an axis along the first bone and thetibia crest 345. Then positioning 5240 the joint to a second targetflexion value (e.g., moving a leg to extension). When the joint is atthe second target flexion value the joint can then be rotated back andforth to obtain the alignment of the second bone. For example one canrotate 5250 the joint about a third point and a fourth point where thethird and fourth points are on opposite sides of the joint, for examplewith the leg in extension the leg can be rotated along the path 101A and102A with a pivot point at the heel to acquire the second alignmentvalue. The second alignment value is saved 5260 (e.g., computer readablememory), where the second alignment value is related to the position ofthe second bone, for example the second alignment value can be theangular relationship between an axis along the second bone and the tibiacrest 345. The first and second alignment values can be used by aprocessor to calculate alignment 5270 of the first bone with regards tothe mechanical axis and/or calculate the alignment of the second bone(e.g., angle between an axis through the second bone and the mechanicalaxis) with regards to the mechanical axis. Note that alignment can bewith regards to other axes, for example the tibia crest 345 instead ofthe mechanical axis.

Note that the rotation 5280 between the first and second points or thethird and fourth points 5290 can be about a pivot point for example theheel or some other chosen pivot point, where the pivot points for eithercan be different but relate to the mechanics of the joint. Note that theprocess of alignment can use a sensor as described above, where thesensor can be zero'd 5295 with respect to a first reference plane and asecond reference plane (e.g., horizontal, vertical planes). For exampleas described above the horizontal plane can be a table top and thevertical plane perpendicular to the table top.

Note that during rotation, measurements 5330 can be taken along thepaths (e.g., along 101A and 102A). The amount of measurements depends onthe sampling rate and the speed of rotation. The measurements can beused by the processor to calculate 5340 the maximum of the arc ofmotion, for example the highest point above the table.

In addition to alignment the measurements can be used to calculate atilt value 5350 that is related to vargus or valgus misalignment. Forexample the measurements 5360 can determine the angles 193A or 195A,which can be measured with respect to various axis (e.g., mechanicalaxis, tibia crest).

Note that the sensor can determine flexion position, for example priorto rotation between the third and fourth points the sensor can providefeedback to a user to flex the joint until an axis of the sensoracquires a desired orientation, for example the horizontal plane of thesensor intersecting the table plane by an angle (e.g., 45 degrees).

FIG. 54 illustrates steps according to an embodiment where thevargus/valgus angle of the first bone can be compared to thevargus/valgus angle of the second bone to calculate 5370 the alignmentof the first and second bones to a reference axis (e.g., mechanicalaxis, tibia crest).

FIG. 55 illustrates a block diagram of at least one embodiment isdirected to a method of measuring alignment 5500 of a tibia to amechanical axis or a tibia crest of a leg which includes the steps of:placing a heel 5510 of a leg in an approximately fixed location;positioning a knee joint 5520 to a target flexion value as measured by asensored insert coupled within the knee joint; rotating the knee joint5530 between a first point and a second point (e.g., as describedabove), where the first and second points are respectively on a medialand lateral side of the knee joint, and where rotating the knee ispivoting on the heal of the leg; and saving an alignment value 5540 ofthe tibia. Additional embodiments, as illustrated in FIG. 56, canfurther include a step of maintaining an ankle in a fixed position 5610relative to the heel. Additional embodiments can further include a stepof positioning the knee joint 5620 where the sensored insert (e.g., aninsert with sensors) is at approximately a 45 degree angle. Additionalembodiments 5690 can further include the steps of rotating the kneejoint 5630 between the first and second points at least two times;measuring data points 5640 over an arc of the anterior-posterior axis;and determining a maximum of the arc 5650 (e.g., as discussed above).

Additional embodiments, for example as illustrated in FIG. 57, canfurther include the steps of calculating a tilt value 5700 of thesensored insert along a medial-lateral line (e.g., in direction 101 and102 respectively) of a proximal end of the tibia; converting the tiltvalue 5710 to a varus or valgus number in relation to a mechanical axisor a tibia crest of the leg for the tibia.

Additional embodiments 5800, for example as illustrated in FIG. 58, canfurther measure the alignment of the femur, for example the process caninclude the steps of positioning a knee joint 5810 to a target flexionvalue (e.g., so that the leg is bent or in extension) as measured by asensored insert coupled within the knee joint; rotating the knee joint5820 between a first point and a second point, where the first andsecond points are respectively on a medial and lateral side of the kneejoint, where rotating the knee is pivoting on a hip joint of the leg;and saving an alignment value 5830 of the femur.

Note that additional embodiments, for example as illustrated in FIG. 59,can include positioning the knee joint 5910 to various orientations forexample where the sensored insert (e.g., coupled to the knee) is atapproximately a 45 degree angle or positioning the leg 5920 inextension.

Additional embodiments 5990, for example as illustrated in FIG. 59, forfemur alignment can include the steps of: rotating the knee joint 5930between the first and second points at least two times where thesensored insert is coupled to a distal end of the femur; measuring datapoints 5940 over an arc of the anterior-posterior axis; and determining5950 a maximum of the arc. Additional embodiments, for example asillustrated in FIG. 60, for femur alignment can include the steps of:calculating a tilt value 6010 of the sensored insert along amedial-lateral line of a distal end of the femur; and converting thetilt value 6020 to a varus or valgus number in relation to a mechanicalaxis of the leg for the femur.

At least one embodiment is directed to methods and devices fordisplaying information to a user to provide information. The informationcan have multiple uses, for example provide feedback for alignmentand/or surgery.

For example at least one embodiment is directed to a graphical userinterface (e.g., 100) on an electronic display (e.g., 105, smart phonescreen, electronic screen, tablet screen, touch screen, projecteddisplay, heads-up display), a memory (e.g., RAM, hard drive, USBremovable memory), and one or more processors (e.g., single processor,RISC, multiply linked processors such as dual processors) to execute oneor more programs (e.g., the software system controlling the feedbackdisplay) stored in the memory, the graphical user interface comprising:a portion of an orthopedic system (e.g., leg, knee joint, hip joint,elbow joint) displayed on the electronic display; a parameter (e.g., CProtation, A-P slope, flexion angle, tibial rotation, tibia angle, medialload on a sensor, lateral load on a sensor, sensor rotation angle, loadlocations) of the orthopedic system displayed on the electronic display;a portion of an orthopedic insert displayed on the electronic display;and a parameter of the orthopedic insert displayed on the electronicdisplay, where in response to detecting movement of the orthopedicsystem the displayed portion of the orthopedic system (e.g., 162) ismoved, a change of the parameter of the orthopedic system is displayed,and a change in parameter of the orthopedic insert is displayed.

In at least one embodiment the parameter of the orthopedic insert is amedial contact location displayed as a symbol or area of contact (e.g.,158A and 158B) on the displayed portion of the orthopedic insert (e.g.,157). In at least one embodiment the parameter of the orthopedic insertis a lateral contact location displayed as a symbol or area of contacton the displayed portion of the orthopedic insert. In at least oneembodiment the parameter of the orthopedic insert is a medial contactload displayed as a range on a display (e.g., BB.BB and AA.AA, in FIG.24). In at least one embodiment the parameter of the orthopedic insertis a lateral contact load displayed as a range (e.g., BB.BB and AA.AA,in FIG. 24) on a display.

At least one embodiment further includes the steps of displaying a dial(e.g., 2900, 3000) that moves in response to movement of the orthopedicsystem. The embodiment can change the color (e.g., from white to blue,yellow to white) of the displayed parameter of the orthopedic systemwhen the value of the parameter of the orthopedic system is within apredetermined range (e.g., +/−1 to 3 degrees of an angular target, +/−1to 5 mm of a translational location) of a target value of the parameterof the orthopedic system. At least one embodiment further includes thesteps of changing the color of the displayed parameter of the orthopedicinsert when the value of the parameter of the orthopedic insert iswithin a predetermined range of a target value of the parameter of theorthopedic insert. Additionally embodiment can change the border (e.g.,3290) around a value when that value has been fixed.

At least one embodiment can combine the GUI system with the measurementsystem. For example at least one embodiment can be directed to a methodof providing feedback of an orthopedic alignment system coupled todisplay comprising: displaying a portion of an orthopedic system on adisplay; displaying a parameter of the orthopedic system in the display;displaying a portion of an orthopedic insert (e.g., a tibia insert) inthe display (e.g., 157); displaying a parameter of the orthopedic insertin the display (e.g., 154D); detecting movement of the orthopedic system(e.g., using accelerometers, magnetometers, GPS, acoustics, mechanicalmeasurements), and moving the displayed portion of the orthopedic systemin response to the movement of the orthopedic system; detecting a changeof the parameter of the orthopedic insert during movement of theorthopedic system; detecting a change of the parameter of the orthopedicsystem during movement of the orthopedic system; displaying the changein parameter of the orthopedic insert in the display; and displaying thechange in parameter of the orthopedic system in the display.

At least one embodiment is directed to measurement of theanterior-posterior slope/tilt. The measurement can be used, for exampleto obtain the A-P slope of a bone cut or of a prosthetic component(e.g., tibial insert) inserted into an orthopedic system. The A-P slopecan provide user (e.g., a surgeon) information to determine theprosthetic component has been placed correctly. For example if, during aknee surgery, all the ligaments are in place the bone cut would not haveany slope. If the PCL were removed, for example, a supporting post is onthe insert and has been found to require an A-P tilt to allow movementin flexion, thus identifying the A-P tilt or angle can be important formore accurate fitting of the prosthetic component.

Thus, for example one embodiment, as illustrated in FIG. 61, can bedirected to a method 6100 of measuring slope or tilt of a prepared bonesurface of a bone comprising the steps of: referencing a three-axisaccelerometer 6110 to a bone landmark (e.g., tibia crest) when the boneis in extension and where the three-axis accelerometer is referenced togravity to measure position and tilt; placing the bone in extension 6120as measured by the three-axis accelerometer; coupling the three-axisaccelerometer 6130 to the prepared bone surface; and measuring the slopeor tilt of the tibial prosthetic component with the three-axisaccelerometer. Note that the accelerometer can be calibrated withrespect to a horizontal and vertical reference. The horizontal referencecan be a table top, while the vertical reference can be perpendicular tothe table top. A detailed discussion of accelerometers is not includedsince it is well known by one of ordinary skill in the arts; howeverU.S. patent application Ser. No. 13/673,921, “Motion and OrientationSensing Module or Device for Positioning of Implants”, containsdiscussion of sensors, bit and memory discussions, and accelerometers,and the Applications content is incorporated by reference in itsentirety.

Note that measuring the slope or tilt 6140 of the tibial prostheticcomponent includes the steps of: measuring the slope or tilt 6150 of theprepared bone surface relative to a bone landmark (e.g., tibia crest,mechanical axis); monitoring the slope or tilt 6160 on a remote system;and storing 6170 (e.g., in computer readable memory) the measured slopeor tilt of the prepared bone surface.

Additional embodiments, as illustrated in FIG. 62, can further includethe step of changing the slope or tilt 6200 of the prosthetic componentafter measurement. Additional embodiments can further include the stepof placing 6210 the three-axis accelerometer (e.g., where theaccelerometer is in a sensor) on a first reference plane (e.g., ahorizontal plane such as a table top); and measuring 6220 the firstreference plane (e.g., recording a first set of data measured by theaccelerometer); reversing a position 6230 of the three-axisaccelerometer on the first reference plane 180 degrees; measuring 6240the first reference plane (e.g., recording a second set of data measuredby the accelerometer); averaging measurements 6250 of the firstreference plane (e.g., averaging the values of the first data set andsecond data set); and zeroing 6260 the three-axis accelerometer toreference to the first reference plane where the first reference planecorresponds to zero acceleration (e.g., gravity). For example the firstand second data sets can include x, y, z values, and the averaging stepcan include averaging all of the x, y, and z values of both data sets.Then to zero the processor can obtain offset x, y, and z values to applyto any measurement so that when a sensor (e.g., with the accelerometerincluded) lies on the first reference plane, the x, y, and z values readabout zero.

As discussed above additional embodiments can include the step ofzeroing 6270 the three-axis accelerometer to a second reference plane(e.g. a plane perpendicular of the first plane).

Additional embodiments 6300, as illustrated in FIG. 63, include thesteps of coupling 6310 a sensored insert in a joint of themuscular-skeletal system where the sensored insert has an articularsurface configured to allow joint movement; and referencing 6320 athree-axis accelerometer to a tibial ridge (e.g., or tibia crest) wherethe tibia is in extension and where the three-axis accelerometer is usedto measure position and tilt.

Additional embodiments 6305 include the steps of inserting 6340 thesensored insert into the knee joint; placing the leg 6350 in extensionas measured by the three-axis accelerometer; and measuring the slope ortilt 6360 of the tibial prosthetic component with the three-axisaccelerometer.

Additional embodiments include the steps of placing a shim 6370 on thesensored insert; and measuring the load applied 6380 by themuscular-skeletal system to the sensored insert where the loading on thesensored insert is within a predetermined load range.

Additional embodiments include the steps of referencing the three-axisaccelerometer 6390 further includes a step of placing a posterior edgeof the sensored insert along the tibial ridge where the three-axisaccelerometer is in the sensored insert.

Additional embodiments 6400, illustrating FIG. 64, include the steps ofholding 6410 the sensored insert vertical along the tibial ridge;monitoring 6420 a vertical position of the sensored insert on a remotesystem; referencing the three-axis accelerometer 6430 to the tibialridge when the sensored insert is within a predetermined vertical range(e.g., typically +−2 degrees).

Additional embodiments include the steps of referencing the three-axisaccelerometer 6440 to the tibial ridge comprises a step of measuring arotation of the sensored insert with the three-axis accelerometer wherethe rotation corresponds to a slope or tilt of the tibial ridge when theleg is in extension.

Additional embodiments, illustrated in FIG. 65, include the steps ofmeasuring the slope or tilt of the tibial prosthetic component includesthe steps of: measuring the slope or tilt 6510 relative to the tibialridge; monitoring the slope or tilt 6520 on a remote system; and storingthe anterior-posterior slope 6530 of the tibial prosthetic component.

Additional embodiments include the step of changing theanterior-posterior (A-P) slope or tilt 6540 of the prosthetic componentafter measurement.

Additional embodiments include the steps of placing the sensored insert6550 on a first reference plane; and measuring 6560 the first referenceplane; reversing 6570 a position of the module on the first referenceplane 180 degrees; measuring 6580 the first reference plane; averaging6590 measurements of the first reference plane; and zeroing 6593 themodule to reference to the first reference plane where the firstreference plane corresponds to zero gravity.

Additional embodiments include the step of zeroing 6595 the three-axisaccelerometer to a second reference plane where the second referenceplane is perpendicular to the first reference plane.

At least one embodiment, as illustrated in FIG. 66, is directed to amethod 6600 of referencing a three-axis accelerometer to measurelocation, tilt, and rotation of the muscular-skeletal system comprisingthe steps of: referencing the three-axis accelerometer 6610 to a firstplane where the three-axis accelerometer is referenced to gravity andwhere the first plane corresponds to zero gravity; referencing thethree-axis accelerometer 6620 to a second plane where the second planeis perpendicular to the first plane; referencing a three-axisaccelerometer 6630 to a bone landmark of a bone when the bone is inextension; placing the bone in extension 6640 as measured by thethree-axis accelerometer; coupling 6650 the three-axis accelerometer toa surface of the bone; and measuring the slope or tilt 6660 of a surfaceof the bone with the three-axis accelerometer relative to the bonelandmark.

Additional embodiments include the steps of coupling 6670 the three-axisaccelerometer to the bone landmark; monitoring 6680 a position of thethree-axis accelerometer on a remote system relative to the first orsecond plane; and referencing 6690 the three-axis accelerometer to thebone landmark when the three-axis accelerometer is within apredetermined range of the first or second plane.

Additional embodiments include the step of measuring 6593 a rotation ofthe three-axis accelerometer when placed on the bone landmark and thebone is in extension. In at least one embodiment the step of measuringthe slope or tilt of the bone surface can include the steps of:monitoring 6595 the slope or tilt on a remote system; and storing 6597the slope or tilt of the bone surface.

Additional embodiments, illustrated in FIG. 67, include the steps ofcoupling 6710 the three-axis accelerometer to a first plane; measuring6720 the first plane; reversing a position 6730 of the three-axisaccelerometer on the first plane 180 degrees; measuring 6740 the firstplane; averaging 6750 measurements of the first plane; and zeroing 6760the three-axis accelerometer to reference to the first plane where thefirst reference plane corresponds to zero acceleration (e.g. gravity).

At least one further embodiment is directed to the determination of themedial-lateral tilt of a bone coupled to a joint. A method of measuringtilt 8100, as illustrated in FIG. 81, of a prepared bone surface of amuscular-skeletal joint comprising the steps of: coupling 8110 athree-axis accelerometer to the prepared bone surface of a bone wherethe three-axis accelerometer measures position and tilt; coupling 8120the bone to a surface; rotating 8130 the joint between two points wherea maximum is located between the two points and where the joint pivotsoff of the surface and where the three-axis accelerometer is referencedto the surface; identifying 8140 where the three-axis accelerometer isat the maximum; and calculating 8150 bone tilt.

Additional embodiments, as illustrated in FIG. 82, include the step ofcomparing 8210 a location of the maximum to a location of a zero tiltmaximum to determine tilt.

Additional embodiments include the step of rotating 8220 the joint sixtimes or less between the two points. Note that there is no limit to thenumber of times rotating the joint can occur.

Additional embodiments include the steps of: capturing 8230 a pluralityof positions of the three-axis accelerometer as the joint is movedbetween a first point to a second point; storing 8240 the plurality ofpositions of the three-axis accelerometer with each movement from thefirst point to the second point and from the second point to the firstpoint; and calculating 8250 the maximum and the position of the maximum.

Additional embodiments include the steps of capturing a plurality ofpositions includes a step of measuring 8260 a location of the three-axisaccelerometer with a 15-bit or greater precision.

Additional embodiments include the steps of rotating 8270 the jointbetween the two points four times or less.

Additional embodiments, as illustrated in FIG. 83, include the step oflimiting movement 8310 of the joint within a predetermined range wherethe maximum is within the predetermined range. For example if one movesa knee about a pivot point from a medial to a lateral side along thepath the knee is at the zenith location, which in this non-limitingexample would be the maximum.

Additional embodiments include the steps of: maintaining 8320 a pivotpoint at a fixed location on the surface; and monitoring 8330 movementof the joint on a remote system where the predetermined range is shownon the remote system whereby a user maintains movement of the jointbetween the predetermined range on the remote system.

At least one embodiment 8400, as illustrated in FIG. 84, is directed toa method of measuring medial-lateral tilt of a prepared bone surface ofa knee joint comprising the steps of: coupling 8410 a tibial prostheticcomponent to a proximal end of a prepared tibia; placing 8420 a sensoredinsert into a tibial tray where the sensored insert includes athree-axis accelerometer to measure position and tilt and where the kneejoint is loaded similar to final joint loading; rotating 8430 between afirst point and a second point respectively on a medial and a lateralside of the knee joint where a maximum is located between the first andsecond points; identifying 8440 where the three-axis accelerometer is atthe maximum; and calculating 8450 bone tilt. Additional embodiments, asillustrated in FIG. 85, include the steps of: referencing 8510 thethree-axis accelerometer to a surface; maintaining 8520 a heel of a legon the surface; and pivoting 8530 the knee joint off of the heel of theleg. Additional embodiments include the step of: comparing 8540 alocation of the maximum to a location of a zero tilt maximum todetermine tilt. Additional embodiments include the steps of: rotating8550 the joint six times or less between the first point and the secondpoint.

Additional embodiments 8600, as illustrated in FIG. 86, include thesteps of: capturing 8610 a plurality of positions of the three-axisaccelerometer as the knee joint is moved between a first point to asecond point; storing 8620 the plurality of positions of the three-axisaccelerometer with each movement from the first point and the secondpoint and from the second point to the first point; and calculating 8630maximum and the position of the maximum. In additional embodiments, asillustrated in FIG. 87, the step of capturing 8710 a plurality ofpositions includes a step of measuring a location of the three-axisaccelerometer with a 15-bit or greater precision. Additional embodimentsinclude the step of: rotating 8720 the joint between the first andsecond points four times or less. Additional embodiments, illustrated inFIG. 88, include the step of: limiting 8810 movement of the joint withina predetermined range where the maximum is within the predeterminedrange. Additional embodiments include the steps of: monitoring 8820movement of the joint on a remote system where the predetermined rangeis shown on the remote system whereby a user maintains movement of thejoint between the predetermined range on the remote system.

At least one embodiment, as illustrated in FIG. 89, is directed to amethod of measuring medial-lateral tilt of a distal end of a femur of aknee joint comprising the steps of: coupling 8900 a sensored insert to adistal end of the femur where the sensored insert includes a three-axisaccelerometer to measure position and tilt and where the knee joint isloaded similar to final joint loading; rotating 8910 between a firstpoint and a second point respectively on a medial and a lateral side ofthe knee joint where a maximum is located between the first and secondpoints; identifying 8920 where the three-axis accelerometer is at themaximum; and calculating 8930 bone tilt.

Additional embodiments include the steps of: referencing 8940 thethree-axis accelerometer to a surface; and pivoting 8950 the knee jointoff of the femoral head of the femur. Additional embodiments include thesteps of: limiting 8960 movement of the joint within a predeterminedrange where the maximum is within the predetermined range wherebyprecision increases by reducing the predetermined range; monitoring 8970movement of the joint on a remote system where the predetermined rangeis shown on the remote system whereby a user maintains movement of thejoint between the predetermined range on the remote system; capturing8980 a plurality of positions of the three-axis accelerometer as theknee joint is moved between the first and second points; storing 8990the plurality of positions of the three-axis accelerometer with eachmovement from the first point and the second point and from the secondpoint to the first point; and calculating 8995 the position of themaximum.

At least one embodiment is directed to system to support kineticassessment, joint modification, and installation of a final prostheticjoint comprising: a sensing insert configured to measure load, positionof load, and joint alignment; a remote system coupled to the sensinginsert configured to receive measurement data from the sensing insertwhere a joint assessment and subsequent changes to affect load, positionof load, and joint alignment are performed under muscular-skeletalloading whereby a final joint installation has similar loading, positionof load, and alignment.

Additional embodiments include: at least one articular surface; aplurality of load sensors underlying the articular surface configured tomeasure load and position of load; and a three axis accelerometerconfigured to referenced to a table or an acceleration value where thethree axis accelerometer is configured to measure tilt and location. Inat least one embodiment the remote system is configured to monitorposition of load on a display and where a correction comprising one ofrotating a prosthetic component or soft tissue tensioning can beperformed under muscular-skeletal loading to move position of load onthe at least one articular surface within a predetermined area range.

In at least one embodiment the sensing insert is configured to measurean offset of a first bone of the joint relative to a mechanical axis andwhere the three-axis accelerometer is configured to provide measurementdata to determine the offset of the first bone. In at least oneembodiment the sensing insert is configured to measure an offset of asecond bone relative to a mechanical axis and where the three-axisaccelerometer is configured to provide measurement data to determine theoffset of the second bone. In at least one embodiment the system isconfigured to determine a total offset relative to a mechanical axis andif the total offset is within a predetermined offset range.

In at least one embodiment the sensored insert is configured to bereferenced to a first plane, where the sensored insert is configured tobe referenced to a second plane that is perpendicular to the first planeand where the first plane corresponds to a zero orientation in thatplane or a zeroed acceleration with respect to that plane.

At least one embodiment 6800, as illustrated in FIG. 68, is directed toa method of kinetic assessment, joint modification, and installation ofa final prosthetic joint comprising: inserting a sensored insert 6810configured to measure load, position of load, and joint alignment into ajoint; transmitting measurement data 6820 from the sensing to a remotesystem; measuring load 6830 on an articular surface of the sensoredinsert; and shimming 6840 the sensored insert until load is within apredetermined load range; and measuring 6850 joint alignment under load.

At least one embodiment further includes the steps of: referencing 6860the sensored insert to a first reference plane where the sensored insertincludes a three-axis accelerometer referenced to gravity; referencing6870 the sensored insert to a second reference plane that isperpendicular to the first plane; and zeroing 6880 the sensored insertsuch that the first reference plane corresponds to zero gravity.

At least one embodiment 6900, illustrating FIG. 69, further includes thesteps of: measuring 6910 position of load with a plurality of loadsensors underlying the articular surface; and adjusting 6920 theposition of load within a predetermined area range. At least oneembodiment further includes the steps of: rotating 6930 a prostheticcomponent and sensored insert to change a position of load; monitoring6940 the position of load on the remote system; and fixing 6950 theposition of the prosthetic component when the position of load is withinthe predetermined area range on the articular surface.

At least one embodiment, as illustrated in FIG. 70, further includes astep of performing a step of soft tissue tensioning 7010 to change theload applied to the articular surface or to change a position of loadapplied to the articular surface. At least one embodiment, asillustrated in FIG. 71, further includes a step of measuring 7110 boneslope of a prepared bone surface. At least one embodiment furtherincludes a step of modifying 7120 the prepared bone surface to be withina predetermined slope range. At least one embodiment further includesthe steps of: measuring 7130 anterior-posterior slope of the preparedbone surface; and measuring 7140 the medial-lateral slope of theprepared bone surface.

At least one embodiment, as illustrated in FIG. 72, further includes thesteps of: measuring 7210 an offset of a first bone of the joint relativeto the mechanical axis where the three-axis accelerometer is configuredto provide measurement data to determine the offset of the first bone;and measuring 7220 an offset of a second bone of the joint relative to amechanical axis and where the three-axis accelerometer is configured toprovide measurement data to determine the offset of the second bone.

At least one embodiment further includes adjusting joint alignment 7230within a predetermined alignment range where a joint assessment andsubsequent changes to affect load, position of load, and joint alignmentare performed under muscular-skeletal loading whereby a final jointinstallation has similar loading, position of load, and alignment.

At least one embodiment, as illustrated in FIG. 73, is directed to amethod of kinetic knee assessment for installing a prosthetic knee jointcomprising: inserting 7300 a sensored insert configured to measure load,position of load, and joint alignment into a knee joint; transmitting7310 measurement data from the sensing to a remote system; measuring7320 load on at least one articular surface of the sensored insert; andshimming 7330 the sensored insert until a load is within a predeterminedload range; measuring 7340 the position of load with a plurality of loadsensors underlying at least one articular surface of the sensoredinsert; measuring 7350 alignment of a femur and tibia relative to amechanical axis of the leg under load with a three-axis accelerometerwithin the sensored insert; and monitoring 7360 loading, position ofload, and alignment on the remote system.

At least one embodiment further includes the steps of: measuring 7370 anoffset of a tibia relative to the mechanical axis undermuscular-skeletal loading; measuring 7380 an offset of a femur relativeto the mechanical axis under muscular-skeletal loading; and combining7390 the offsets to determine an alignment relative to the mechanicalaxis of the leg. At least one embodiment further includes a step ofmeasuring 7393 the anterior-posterior slope of a proximal end of thetibia.

At least one further embodiment is directed to measuring and/ordisplaying contact information. The contact information can be usefulsince the prosthetic component can be rotated to change the position ofload. Therefore the amount of rotation can be recorded, displayed andused. In at least one embodiment the contact information is recorded.Note that contact information can affect subsequent measurements.

For example at least one embodiment, as illustrating in FIG. 74, isdirected to a method 7405 of adjusting a contact point of a joint systemwhere a prosthetic component is coupled to a bone comprising the stepsof: placing a sensored insert 7410 in the joint where the sensoredinsert has an articular surface, a plurality of load sensors coupled tothe articular surface, and a three-axis accelerometer to measureposition, tilt, and rotation; monitoring 7420 position of load on thearticular surface on a remote system where the sensored insert isconfigured to send load data to the remote system; repositioning 7430the prosthetic component relative to a bone to change the contact pointto the articular surface; and fixing a position 7440 of the prostheticcomponent when the position of load is within a predetermined area rangeof the articular surface.

At least one embodiment further includes the step 7450 of changing aposition of the prosthetic component. At least one embodiment furtherincludes a step of rotating the prosthetic component. At least oneembodiment further includes a step of soft tissue tensioning 7470 tomove the position of load on the articular surface. At least oneembodiment further includes a step of pinning 7460 the prostheticcomponent to the bone where pinning holds the prosthetic component tothe bone but allows repositioning to change position of load.

At least one embodiment 7500, as illustrated in FIG. 75, furtherincludes the steps of: coupling 7510 the sensored insert to theprosthetic component; positioning 7520 the joint in extension where thethree-axis accelerometer is referenced to gravity and where thethree-axis accelerometer detects when the bone is in extension;positioning 7530 the prosthetic component or sensored insert to bealigned to a predetermined location; and zeroing 7540 the prostheticcomponent such that the contact point position of the prostheticcomponent is zero at the predetermined location.

At least one embodiment, as illustrated in FIG. 76, further includes astep of aligning 7610 the prosthetic component or sensored insert to abone landmark. At least one embodiment further includes a step ofaligning 7620 the prosthetic component or sensored insert to amechanical axis of the joint. At least one embodiment further includesthe steps of: rotating 7630 the prosthetic component to adjust aposition of load; monitoring 7640 the position of load on the remotesystem; fixing 7650 the position of the prosthetic component when acontact point on the articular surface is within a predetermined arearange; and storing 7660 an amount of rotation from the predeterminedlocation.

At least one embodiment 7700, as illustrated in FIG. 77, is directed toa method of adjusting a tibial prosthetic component in a knee jointcomprising the steps of: coupling 7710 a tibial prosthetic component toa tibia; coupling 7720 a sensored insert to the tibial prostheticcomponent where the sensored module has at least one articular surface,a plurality of pressure sensors coupled to the articular surface, and athree-axis accelerometer to measure position and tilt; rotating 7730 thetibial prosthetic component relative to the tibia; monitoring 7740position of load on the articular surface where the sensored insert isconfigured to send load data to the remote system; and fixing 7750 aposition of the tibial prosthetic component when a contact point on thearticular surface is within a predetermined area range.

At least one embodiment further includes a step of soft tissuetensioning 7760 to move the position of load on the articular surface.At least one embodiment further includes a step of pinning 7770 thetibial prosthetic component to the tibia where pinning holds the tibialprosthetic component to the tibia but supports rotation of the tibialprosthetic component.

At least one embodiment, as illustrated in FIG. 78, further includes thesteps of: placing 7810 the sensored insert into a tibial tray of thetibial prosthetic component; positioning 7820 a femur and tibia inextension where the three-axis accelerometer is referenced to gravityand where the three-axis accelerometer detects when the bone is inextension; positioning 7830 the tibial prosthetic component or sensoredinsert to be aligned to a predetermined location; and zeroing 7840 thetibial prosthetic component such that the contact point position of thetibial prosthetic component is about zero at the predetermined location.

At least one embodiment further includes a step of aligning 7850 thetibial prosthetic component or sensored insert to a bone landmark. Atleast one embodiment further includes a step of aligning 7860 the tibialprosthetic component or sensored insert to a mechanical axis of thejoint.

At least one embodiment further includes a step of storing 7870 anamount of rotation of the tibial prosthetic component when the tibialprosthetic component position is fixed.

At least one embodiment 7705, as illustrated in FIG. 79, furtherincludes the steps of: placing 7910 the sensored insert having a firstarticular surface and a second articular surface into the knee jointwhere the sensored insert is coupled to a tibial tray of the tibialprosthetic component; positioning 7920 a femur and tibia in extensionwhere the three-axis accelerometer detects when the bone is inextension; positioning 7930 the tibial prosthetic component or sensoredinsert to be aligned to a predetermined location; and zeroing 7940 theprosthetic component such that the contact point position of the tibialprosthetic component is zero at the predetermined location.

At least one embodiment further includes the steps of: monitoring 7950position of load on the first and second articular surfaces; androtating 7960 the tibial prosthetic component relative to the tibiauntil the position of load of each articular surface is within apredetermined area range; and measuring 7970 and storing the rotationrequired to place the position of load on the first and second articularsurface within the predetermined are range.

At least one embodiment, as illustrated in FIG. 80, further includes thesteps of: performing soft tissue tensioning 8000; monitoring 8010 loadon the first and second articular surfaces; and adjusting 8020 loadingrespectively on the first articular surface and the second articularsurfaces to be within a first predetermined load range and a secondpredetermined load range.

At least one embodiment is directed to a system for adjusting contactposition of a muscular-skeletal joint comprising: a prosthetic componentconfigured to rotate after being coupled to a bone; a sensored inserthaving an articular surface where the sensored insert is configured tocouple to the prosthetic component, where the sensored insert has aplurality of pressure sensors coupled to the articular surface and athree-axis accelerometer to measure position and tilt, and where thethree-axis accelerometer is referenced to gravity; a remote systemconfigured to wirelessly receive position of load data from the sensoredinsert where the remote system is configured to display the articularsurface, where the remote system is configured to display position ofapplied load to the articular surface, and where the remote system isconfigured to store a zero contact point where the bone and prostheticcomponent are aligned.

In at least one embodiment the remote system is configured to display apredetermined area range on the articular surface, where the remotesystem is configured to indicate positions of flexion of the bone, wherethe remote system is configured to store an amount of rotation of theprosthetic component relative to the zero contact point where rotatingthe prosthetic component changes a position of applied load to thearticular surface.

While the present invention has been described with reference toparticular embodiments, those skilled in the art will recognize thatmany changes may be made thereto without departing from the spirit andscope of the present invention. Each of these embodiments and obviousvariations thereof is contemplated as falling within the spirit andscope of the claimed invention, which is set forth in the claims. Whilethe subject matter of the invention is described with specific examplesof embodiments, the foregoing drawings and descriptions thereof depictonly typical embodiments of the subject matter and are not therefore tobe considered to be limiting of its scope, it is evident that manyalternatives and variations will be apparent to those skilled in theart. Thus, the description of the invention is merely descriptive innature and, thus, variations that do not depart from the gist of theinvention are intended to be within the scope of the embodiments of thepresent invention. Such variations are not to be regarded as a departurefrom the spirit and scope of the present invention.

While the present invention has been described with reference toembodiments, it is to be understood that the invention is not limited tothe disclosed embodiments. The scope of the following claims is to beaccorded the broadest interpretation so as to encompass allmodifications, equivalent structures and functions. For example, ifwords such as “orthogonal”, “perpendicular” are used the intendedmeaning is “substantially orthogonal” and “substantially perpendicular”respectively. Additionally although specific numbers may be quoted inthe claims, it is intended that a number close to the one stated is alsowithin the intended scope, i.e. any stated number (e.g., 90 degrees)should be interpreted to be “about” the value of the stated number(e.g., about 90 degrees).

As the claims hereinafter reflect, inventive aspects may lie in lessthan all features of a single foregoing disclosed embodiment. Thus, thehereinafter expressed claims are hereby expressly incorporated into thisDetailed Description of the Drawings, with each claim standing on itsown as a separate embodiment of an invention. Furthermore, while someembodiments described herein include some but not other featuresincluded in other embodiments, combinations of features of differentembodiments are meant to be within the scope of the invention, and formdifferent embodiments, as would be understood by those skilled in theart.

What is claimed is:
 1. A method of measuring slope or tilt of a tibialprosthetic component coupled to a tibia comprising the steps of: placinga leg in a predetermined position; coupling a prosthetic componenthaving a position measurement system against a bone landmark of thetibia wherein the prosthetic component is not in the prosthetic kneejoint, wherein the prosthetic component is configured to measure areference position, and wherein the prosthetic component includes atransmitter configured to transmit measurement data; receivingmeasurement data from the prosthetic component wherein a computerreceives the measurement data, wherein the reference position is storedin memory coupled to the computer, and wherein the reference positioncorresponds to the predetermined position of the leg.
 2. The method ofclaim 1 further including a step of measuring position with an inertialsensor.
 3. The method of claim 1 further including a step of placing theleg in extension.
 4. The method of claim 1 further including a step ofmeasuring position with an accelerometer.
 5. The method of claim 1wherein the step of measure a reference position comprises the steps of:holding the prosthetic component approximately vertical along a tibialridge of the tibia; measuring a position of the prosthetic component inreal-time with the position measurement system; referencing theprosthetic component to the tibial ridge when the sensored insert iswithin a predetermined vertical range wherein the reference position isstored in memory coupled to the computer.
 6. The method of claim 1further including a step of measuring the reference position when theprosthetic component is within plus or minus 2 degrees of vertical. 7.The method of claim 1 further including the steps of: placing aposterior edge of a sensored insert against the tibial ridge wherein thesensored insert is the prosthetic component; and storing a verticalposition of the sensored insert in memory coupled to the computer. 8.The method of claim 1 further including the steps of: inserting theprosthetic component into the prosthetic knee joint wherein the leg canbe moved through a range of motion; placing the leg in extension whereinthe computer compares the position of the leg to the reference position;and measuring the slope or tilt of a tibial tray of the tibialprosthetic component with the position measurement system wherein theposition measurement system measures position, rotation, and slope. 9.The method of claim 8 further including a step of measuring the loadapplied by the muscular-skeletal system to the prosthetic componentwherein the prosthetic component is a sensored insert having a pluralityof load sensors and wherein the load measurement data is sent to thecomputer and stored in memory coupled to the computer.
 10. The method ofclaim 1 further including the steps of: placing the prosthetic componenton a first reference plane; and measuring the first reference plane;reversing a position of the prosthetic component on the first referenceplane 180 degrees; measuring the first reference plane; averagingmeasurements of the first reference plane wherein the computer receivesthe measurement data and is configured to average the measurementsrelated to the first reference plane; and zeroing the prostheticcomponent to reference to the first reference plane wherein the computeris configured to identify the first reference plane to zero gravity. 11.The method of claim 10 further including a step of zeroing theprosthetic component to a second reference plane where the secondreference plane is perpendicular to the first reference plane whereinthe computer is configured to identify the second reference plane. 12.The method of claim 1 further including a step of measuring positionwith an accelerometer.
 13. The method of claim 1 further including astep of placing the leg in extension.
 14. The method of claim 13 furtherincluding a step of placing the prosthetic component against a bonelandmark of the tibia wherein the prosthetic component is a sensoredinsert.
 15. The method of claim 14 further including the steps of:holding the sensored insert approximately vertical along a tibial ridgeof the tibia; measuring a position of the sensored insert in real-time;referencing the sensored insert to the tibial ridge when the sensoredinsert is within a predetermined vertical range wherein the referenceposition is stored in memory coupled to the computer.
 16. The method ofclaim 14 further including a step of measuring the reference positionwhen the sensored insert is within plus or minus 2 degrees of vertical.17. The method of claim 16 further including the steps of: placing aposterior edge of the sensored insert against the tibial ridge; andstoring a vertical position of the sensored insert in memory coupled tothe computer.
 18. A method of measuring slope or tilt of a tibialprosthetic component coupled to a tibia comprising the steps of: placinga leg in extension; coupling a sensored insert having a positionmeasurement system to the tibial ridge of the tibia wherein the sensoredinsert is not in the prosthetic knee joint, wherein the sensored insertis configured to measure a reference position, wherein position ismeasured in real-time with an inertial sensor, and wherein the sensoredinsert includes a transmitter configured to transmit measurement data;referencing the sensored insert to the tibial ridge when the sensoredinsert is within a predetermined vertical range; receiving measurementdata from the sensored insert wherein a computer receives themeasurement data, wherein the reference position is stored in memorycoupled to the computer, and wherein the reference position correspondsto the predetermined position of the leg.
 19. The method of claim 18further including a step of measuring the reference position when thesensored insert is within plus or minus 2 degrees of vertical.
 20. Themethod of claim 19 further including the steps of: placing a posterioredge of the sensored insert against the tibial ridge; and storing avertical position of the sensored insert in memory coupled to thecomputer.
 21. The method of claim 18 further including the steps of:inserting the sensored insert into the prosthetic knee joint wherein theleg can be moved through a range of motion; placing the leg in extensionwherein the computer compares the position of the leg to the referenceposition; and measuring the slope or tilt of a tibial tray of the tibialprosthetic component with the position measurement system wherein theposition measurement system measures position, rotation, and slope. 22.The method of claim 21 further including a step of measuring the loadapplied by the muscular-skeletal system to the sensored insert whereinthe sensored insert includes a plurality of load sensors and wherein theload measurement data is sent to the computer and stored in memorycoupled to the computer.
 23. The method of claim 18 further includingthe steps of: placing the sensored insert on a first reference plane;and measuring the first reference plane; reversing a position of thesensored insert on the first reference plane 180 degrees; measuring thefirst reference plane; averaging measurements of the first referenceplane wherein the computer receives the measurement data and isconfigured to average the measurements related to the first referenceplane; and zeroing the sensored insert to reference to the firstreference plane wherein the computer is configured to identify the firstreference plane to zero gravity.
 24. The method of claim 23 furtherincluding a step of zeroing the prosthetic component to a secondreference plane where the second reference plane is perpendicular to thefirst reference plane wherein the computer is configured to identify thesecond reference plane.
 25. A method of measuring slope or tilt of atibial prosthetic component coupled to a tibia comprising the steps of:placing the prosthetic component on a first reference plane; andmeasuring the first reference plane; reversing a position of theprosthetic component on the first reference plane 180 degrees; measuringthe first reference plane; averaging measurements of the first referenceplane wherein the computer receives the measurement data and isconfigured to average the measurements related to the first referenceplane; and zeroing the prosthetic component to reference to the firstreference plane wherein the computer is configured to identify the firstreference plane to zero gravity; placing a leg in a predeterminedposition; coupling a prosthetic component having a position measurementsystem to the tibia wherein the prosthetic component is not in theprosthetic knee joint, wherein the prosthetic component is configured tomeasure a reference position, and wherein the prosthetic componentincludes a transmitter configured to transmit measurement data;receiving measurement data from the prosthetic component wherein acomputer receives the measurement data, wherein the reference positionis stored in memory coupled to the computer, and wherein the referenceposition corresponds to the predetermined position of the leg.
 26. Themethod of claim 25 further including the steps of: inserting theprosthetic component into the prosthetic knee joint wherein the leg canbe moved through a range of motion; placing the leg in extension whereinthe computer compares the position of the leg to the reference position;and measuring the slope or tilt of a tibial tray of the tibialprosthetic component with the position measurement system wherein theposition measurement system measures position, rotation, and slope. 27.The method of claim 26 further including a step of measuring the loadapplied by the muscular-skeletal system to the prosthetic componentwherein the prosthetic component is a sensored insert having a pluralityof load sensors and wherein the load measurement data is sent to thecomputer and stored in memory coupled to the computer.
 28. The method ofclaim 27 further including a step of zeroing the prosthetic component toa second reference plane where the second reference plane isperpendicular to the first reference plane wherein the computer isconfigured to identify the second reference plane.